Urban Sonic Phenomena and Design

Every city has a unique set of sounds. Despite the omnipresence of sound, designers have made rare attempts to create urban spaces that consider the aural sense as the primary target. Parameters that determine the sonic character of a city include cultural influences such as language and religion. Technology and constant change add a set of sonic events to the urban soundscape: The larger and older the city, the greater and more complex the sonic character.

Literature shows a division in response to this urban sonic feature. Some researchers embrace it as a token of the greatest achievement and testament to the progress of the species (CHENEVY, 1920). Such research aligned with the opposing side argues that noise is a sign of the stagnation of civilisation. If the “Big City” pandemonium was once thought to be a sign of progress in the early twentieth century, this is no longer the case (SCHAFER, R. Murray, 1993). Sonic events are not distributed uniformly within the city; rather, acoustical character changes owing to differences in social and programmatic organisation between districts, morphology, urban texture and geographic location. This section discusses urban sound character, main principles and spatial relationships to determine the urban soundscape.

Soundscape

Soundscape, a concept first formulated by R. Murray Schafer in 1977, is a discipline that mixes aural architecture and sound sources. It is not simply the sum of simultaneously broadcasting tonal signals nor is it merely a by-product of architecture. The term soundscape is the dynamic sonic equivalent of the phrase landscape; it is an integral essence of the environment and exists when the landscape is used. Existing literature attempts to classify sound in various ways. Pierre Schaeffer’s sound classification charts a paradigm that links the sonic event to the object that creates it. In addition to the physical description, each sonic event is classified according to a number of properties, including distance from the receiver, strength in ambience, environment reflectivity and the relationship of the sound to the larger context (SCHAFER, R. Murray, 1993).

Schafer classifies soundscape sound into six main categories with various subcategories, including natural, human, cultural, mechanical, indicator sounds and the absence of sound (i.e., silence). This method measures the beginning (attack), middle (body) and end (decay) of the sound against its duration, frequency and dynamics (SCHAFER, R. Murray, 1993). Many sonic disciplines know and use these terms extensively. The attack is the onset of the event accompanied by an electrostatic noise: The more sudden the attack, the more powerful the sound. If the sound is gradual, the electrostatic noise is less present and even tonality occurs. The body is the middle part of a sonic event, and the ear perceives this signal as ‘stationary.’ Some sounds do not have a body (e.g., bells and gongs). The decay is the time lapse from when the end of the sound to the point at which the sound energy decays to one millionth of its original strength (REAS, Casey and Fry, Ben, 2007). In addition to the mentioned physical and perceptual properties, these three sound attributes are significant derivatives of the volume and shape of an urban arena (SCHAFER, R. Murray, 1993).

An Adapted Diagram of Soundscape classifications. The diagram shows the attack, body, and decay of different urban sounds as per Schafer’s devised technique. Original Diagram Reference: (SCHAFER, R. Murray, 1993)

The volume of a large-scale urban arena depends on the sonic property of the target sound and acoustic geography. The geomorphology and macroclimate of the area are natural shaping factors, and urban morphology and materiality are synthesised factors. Geological formations can act as sound barriers or sound conduits. Steep terrain casts large sound shadows while valleys propagate the target sound across large distances. Vegetation is another parameter of auditory demarcation. Grass reduces the reflectivity of the ground and trees absorb airborne sound waves, which casts large sound shadows. A forest on the outskirts of a town creates a thick vegetation edge that stops the propagation of any sound wave. Effectively, the forest acts as a visual and aural barrier, and delineates and aligns the urban arena within the boundaries of a town. Calm bodies of water act as sound reflectors, which increase the size of the urban arena. Conversely, high windshield factors and turbulence along coastlines affect the directionality of sound waves and cause high interference, which can reduce the volume of the urban arena where the coastline is beyond the threshold (BLESSER, Barry and Salter, Linda-Ruth, 2006).

A suburban area after a heavy snowstorm produces similar properties to an anechoic space. Snow is a highly absorbent medium, and if it covers the ground thoroughly, a receiver can detect only direct sound waves. Opaque spaces occur in urban settings in different forms. Small alleys in densely built areas create the effect of an acoustically opaque small space. Buildings act as sound barriers and reflect low-frequency sounds. Pedestrian tunnels, spaces under bridges and narrow streets between high-rises produce the same acoustical effect. Alleyways between suburban gardens where fences and hedges could impede visual interaction and allow sonic permeation are examples of acoustically transparent urban spaces (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Soundmarks

Traditional city networks evolve around a central public space with defined landmarks. Scholars find that these foci usually have socially significant landmarks associated with unique sounds, namely soundmarks. Soundmarks customarily create large urban arenas. Traditionally, anyone who lives beyond the aural space (i.e., cannot hear it) is not considered a citizen of that town (Blesser & Salter, 2006). Corbin (1998) states that an elevated sense of territorial identity is a direct result of soundmarks and regular aural urban architecture.

Individuals of different ethnic, socioeconomic, and social backgrounds who live in the same region and who are subjected to the same set of sounds recognise these sounds as ‘home.’ Research finds that aural heritage induces a sense of belonging to a community and national pride when residents hear these soundmarks (Corbin, 1998). Soundmarks can also vary in scale and dynamics. For example, a regular peddler chanting the same tune every day is a dynamic soundmark that may link a number of districts. Trains are another type of dynamic soundmark. A less obvious example of aural heritage is the national morning news tune that emanates from the radio. This type of sonic events creates acoustic arenas that can potentially cover countries (Blesser & Salter, 2006).

 An image of the thirty-eight bells for the Abbey of Saint Amand Les Eaux Image Reference: (MYGOLA)

An image of the thirty-eight bells for the Abbey of Saint Amand Les Eaux Image Reference: (MYGOLA)

Soundmarks are also associated with social hierarchy. Societies have established power, time and cultural identity by giving significance to soundmarks. Cultures preceding the industrial revolution adopted human vocals as soundmarks (Blesser & Salter, 2006). During the industrial revolution, a common soundmark in the western world was the bell, in which only the most prestigious and powerful institutions invested (e.g., churches, monasteries, civil governments and entrepreneur factories).

Bells held power in Europe for an exceedingly long time. In 1784, the French went so far as to cast thirty-eight bells for the Abby of Saint Armand Les Eaux to create the largest aural arena possible. The number and synchronisation of bell towers connected close parishes within the amplified arena. Considering the importance of bells, their loss, capture, or destruction were common practices by invading armies as signs defeat. In 1813, Napoleon followed a well-established sixteenth-century tradition of melting down bells as a sign of power inauguration (Corbin, 1998).

Another common soundmark is the clock. The term ‘clock’ derives from the Middle English word ‘clok,’ which is a Middle Dutch and German word for bell. This word appeared with the earliest mechanical timepieces in Europe during the fourteenth century found in monasteries to inform pious monks of prayer times. These timepieces were designed to sound time, not show it, and they became communal foci. At the time, some argued that the clock was the most notable invention, not the steam engine, and the associated sonic event created a culture of efficiency and punctuality. During the industrial revolution, clocks became a means to ‘synchronise men’ who lived in worker towns near factories. Clocks became linked to factory whistles, which sounded to inform workers of shift change intervals (Levine, 2006).

In the East, early Islamic townships also employed soundmarks to establish time (i.e., prayer time), power and territory. The acoustic geography of the region and primitive available technologies prompted human vocal soundmarks. The designated person (Moazen) was chosen for the quality of his voice, and was given social status and bodily protection during war. At designated prayer times, the Moazen took to the highest vantage point to establish the largest aural arena possible. Moazens climbed tall towers or ‘minarets’ built to project the prayer calls across large areas. At the height of the Islamic empire, the status moved from person to architecture. Gradually, the height and number of towers, along with the volume of the arenas centred on them became significant signs of power (Bianca, 2000).

Acoustical Arenas and Urban Spaces

Parallels and Divergences

Aural and urban design theories share commonalities in spatial concepts. Humans live in the built and natural environments and create an aggregation of human-shaped atomically indivisible units. Programmatic designations and social unit structures determine both types of territories. These associations are the result of the corresponding relationship between the city and soundscape. Urban factors, activities and morphologies determine the aggregate pattern of aural spaces. In turn, sonic character affects social order within urban patches. Aural designs do differ from urban designs in a number of order aspects owing to the ascents of physical restrictions such as gravity and the physical nature of sound. This section draws parallels and contrasts between these two concepts.

Design Theory

A Conceptual diagram of the interplay between sonic arenas. [Top - Left] A separate sonic arena.[Top - Right] A group of independent sonic arenas within a larger arena centred on a broadcasting event - All sources are perceived. [Middle - Left] Three sonic arenas centred on identical events, with different relative maximum intensities. The shared sound is amplified in the overlapping zone. [Middle - Right] Two sonic arenas centred on two different sonic events. Neither sound is perceived within the interference zone. [Bottom] A diagram showing the aggregation of sonic arenas in a 3D space. The laws of gravity do not stop the 3D aggregation of aural spaces. The Physical space should be assembled to allow users to perceive the configuration.

Aural design units follow the same principles of atomic indivisibility. Acoustic arenas are the equivocal components of rooms. These aural spaces can be aggregated to create larger and more complex soundscape patterns within urban spaces. For example, the acoustic signature of the public square at the Covent Garden in London corresponds to the activities held in its subdomains, including cafés, markets and performances. These separate domains have associated arenas that are in a continual interplay that define the volume, shape and intermediate threshold zones of the arenas that create the sonic patterns of the space [Refer to: Figure 3. 15]. Amplified sonic events (using microphones and speakers) form large aural spaces that interfere with and affect the volume of other activities. Conversely, domains may contain an aggregation of aural subdomains (e.g., normal conversations at individual tables in a café). These types of subspaces are centred on human voices that occur within a certain frequency band. The collective events amplify the effect of the aural space in the café and encroach upon adjacent aural arenas.

A perpetual occurrence of sound energy exists as the difference between these two types of spaces, and design concepts reflect this divergence. No equivalent concept exists of the street-building pattern relationship in aural design. Rather, the threshold zones between arenas are those regions where a receiver cannot recognise and consciously interpret a sonic event. In these threshold zones, the receiver detects sound energy as ambient sound. Another contrasting factor is the effect of physical elements, as gravity does not prevent a three-dimensional aggregation of acoustic arenas. In this case, the aural design informs the physical configuration. Supporting spaces (e.g., mezzanine levels) are designed to enable the receiver to experience the three-dimensional pattern.

Order & Growth

Aural design is successful when the volume allows for its designated spatial use, and the size and number of users that inscribed the volume and form an aural arena. For example, at an outdoor concert, the broadcasted sonic event located at the stage should be heard clearly throughout the entire space. Curbing external interference and spatial design techniques ensure that the aural arena encompasses the entire audience. Soundscapes and sonic patterns flow and inform the urban morphology.

If Stephen Marshall’s concept that the social structure of a city follows a characteristic order is taken as true, then aural urban design would follow that same order. Social groups create acoustic territories with specific aural codes that identify cohesive social structures. For example, the Heathrow Express train has designated silent cars where it is considered discourteous to speak on the phone. The same code holds true for American suburbia (LABELLE, Brandon, 2010). Thresholds between communities and aural arenas have blurred demarcations, and the volumes and patterns of urban acoustic subdomains follow urban patch morphology, which is a direct result of inhabiting social group order.

Historically, the foci of concentric growing traditional cities were central squares or markets that had specific acoustical signatures or soundmarks. Evidence shows that the location of a soundmark and the volume of the resulting arena within a town are significant factors that determine the morphology of growth. A series of acoustic arenas associated with activities conducted in the extending areas translates and informs the growth of a town. These aural spaces characteristically decrease in SPL and volume as the distance from the central square and the resolution of the street increases. The acoustical signatures of central squares also have a reciprocal relationship with the climate, culture, technology and economics of a city. The density of the aural space network follows that of the urban pattern.

Networking

A diagram showing the sound pressure attenuation within a sonic arena centred on a soundmark. The order of Sonic Arenas, sound pressure and ambient sound follow the urban hierarchical order it exists in.

Urban public spaces are programmatically movement domains. The spatial organisation of these networks is a direct result of information flow. Sonic events are a large subset of this information, and they have a reciprocal relationship with the morphology of these spaces. The characteristic hierarchy of these elements is also reflected in the density of aural arenas that occur within these spaces. As such, SPL and the number of sonic events dissipate outward from the centre and follow the hierarchical fractal structure of the network.

The topology of traditional urban networks is a highly connected configuration. The permeability of this network decreases to create narrow spaces as the distance increases from the central square. The resulting spaces are acoustically opaque owing to the circumscribing mass of the buildings. Except for soundmarks, sonic events that occur in central squares seldom permeate through these spaces. The attenuation of sonic events within an impermeable urban fabric creates navigational cues that steer citizens through the public-private gradient. These cues include change in SPL, tonal coloration of low frequencies reflected within tight spaces, and acoustic shadows of distant sounds. Sound pressure levels and ambient sounds become a reciprocal interpretation of the private-public spatial configuration.

Public Spaces & Interstitial Spaces

A diagram showing the Private- Public Exclusive-Inclusive relationships for aural spaces. [Top-Left] Public all inclusive public space. There is always a level of sound pressure [Top-Right] 2 exclusively private domains. Public arenas may affect the private spaces. [Bottom-Left] ‘archipelago’ ordered private sub-domains with direct access to an all encompassing public space. [Bottom -Right] Public-private gradient: Nested public spaces with exclusive restrictions.

The aural arenas associated with public spaces follow the same private-public topological order of subdomains. Domains can be mutually exclusive, nested, or in archipelago order. The ephemeral attribute of sound allows for the amalgamation of these topologies. In the absence of physical dividers between domains, the manipulation of physical attributes is key in creating social filters. Ground level changes create social filters, and the qualities of sound define elevation and amount of grade change. For example, an elevated stage creates an exclusive physical domain, and the sonic event that occurs in that space forms an inclusive aural arena, while a fully submerged area (e.g., Vietnam Memorial) creates both an exclusive space and aural arena.

In Conclusion

Urban design theory informs this research in that a city is an aggregation of indivisible atomic units. The relationship between these units follows a specific order that results in what is identified as city shapeness. Social logic also defines the growth morphology and network configuration of urban components. Similarly, aural design units are atomically indivisible and aural arenas are sound subcomponent equivalents of physical rooms. Aggregating these subcomponents creates a large and complex urban component or soundscape of the urban space. The aural unit is a sonic event or a sound that occurs within a space and creates a dynamic domain centred on it, namely an acoustic arena. Humans perceive this domain aurally and recognise it as a territory with social coherence. The form and volume of acoustic arenas are determined by the physical properties of the sonic event and the materiality and geometry of the space.

Acoustic Arenas and the Spatial Formation of Aural Spaces

Auditory spatial awareness is a neurological reaction (conscious and unconscious) to spatial acoustics and is one information channel through which the auditory organ receives stimuli. This cognitive process transforms raw sensation into awareness by triggering an elevated state of mental and physical awareness. The response associated with auditory spatial awareness has three stages: detection, recognition and consciousness.
Detection is a raw biological and physiological response. Recognition and consciousness are conditioned by environmental exposure and are learnt associations. The individual perceiving the sound (i.e., sonic event) is the receiver and the resulting vibrations are transformed into neural signals. If detection is established, the receiver is considered within the aural space of the sonic event, also known as the ‘acoustic arena.’ Architects and designer may influence the programmatic aspects of the space directly, but occupants have control over the dynamics of the aural space design. Activities within these spaces create sonic events as the size of the acoustic arena changes (BLESSER, Barry and Salter, Linda-Ruth, 2006). This post discusses the principles of acoustic arenas and the spatial formation of these aural spaces.

Form and Delineation

A superimposed diagram on Pierre Auguste Renoir, Luncheon of the Boating Party (1880-81) [Underlay] The diagram shows different scales of acoustic arenas.

Aural architectural space design follows the principles of acoustic arenas. If a sonic event is sufficiently powerful and a group of receivers detects it, an acoustic arena is formed, which is the volume centred on the sonic event. Anyone who cannot hear this sound, even if unable to detect the source visually, is considered beyond the boundary of the arena. Such sound is beyond the receiver’s ‘acoustical horizon,’ a dynamic auditory space centred on the receiver.

Arena volumes are as dynamic as the activities that generate sonic events. At any given time, the receiver can exist in multiple arenas, intermittently or simultaneously (BLESSER, Barry and Salter, Linda- Ruth, 2006). A successful acoustical design can exploit this interplay by enhancing the auditory connection between a particular sonic event and the listener. This connection is known as and defined by the sonic properties of the ‘auditory channel’.

The view from the whispering gallery in St Paul’s Cathedral in London. Image by Aiwok

The properties and the background ambient sounds of a sonic event define the form of the aural space. Acoustic arenas are in constant interplay, and one arena can encroach upon, substitute, or entirely engulf another. Like a visual partition, the auditory demarcation delineates the boundaries of the arena or horizon. This threshold depends on the physical qualities of the sound and the perceptual response of the listener, which blurs the perimeter. The interplay between arenas creates intermediate zones of acoustical interference where detection, recognition and consciousness do not occur.

Acoustic arenas have unusual configurations compared to other known physical spaces. For example, in a whispering gallery, one arena can exist in two non-contiguous physical areas, simultaneously [1]. If one sonic event dominates a room, the aural boundary may align with or
extend beyond its physical boundaries. Alternatively, the activities could create a matrix of aural arenas with interference zones that act as virtual cubicles within the physical boundaries (BLESSER, Barry and Salter, Linda-Ruth, 2006).

This set of basic acoustic arena principles is the foundation of the algorithm and paradigm used in this study. The volume and shape of an arena are highly dependent on the sensory modality and physical attributes of the sound and surrounding space. In the abstract, an arena exists in free space as a spherical form. The reflectivity and form of the adjacent surfaces have a direct effect on the shape and volume of the aural space and its location (BLESSER, Barry and Salter, Linda-Ruth, 2006). For example, Bill Fontana’s technique of targeting sound energy toward a specific wall manipulates the shape of his designed aural domains (DUFF, Simon, 2011).

Physical and perceptual: Scale and Volume

The scale of the three-dimensional aural space is related directly to loudness (i.e., volume in m3). Designers can use sound intensity and the surrounding absorption coefficient of the material to manipulate volume. Aural sensory design is a hybrid of two juxtaposing concepts, the physics of sound and the human perceptual response. Volume depends on the perceptual response to the frequency of the sonic arena; low-frequency sonic events create small arenas (TURNER, John and Pretlove, A.J., 1991). A physical space with highly reflective surfaces creates significantly large acoustic spaces and vice versa. An aural designer can increase the volume of an arena without increasing reverberation time by creating strong reflections that reach the listener shortly after the direct sound, as they are detected as one strong aural channel (BLESSER, Barry and Salter, Linda-Ruth, 2006).

In the abstract, the volume of an arena centred on one sonic event with no interference is considered to propagate uniformly in all directions to create a spherical space. Energy loss defines the distance from the sonic event to the edge of the aural space (i.e., radius of a spherical arena). Sound energy is absorbed as waves that travel through the air and reflect off surfaces. Sound is measured by different units; the perception of sound is measured along a logarithmic decibel scale (dB) and is often referred to as sound pressure levels (SPL). The smallest change the human ear can detect is 1-3 dB (TURNER, John and Pretlove, A.J., 1991).

The size of an acoustic arena and the enveloping shape of the auditory demarcation are directly related to the decibel scale. This phenomenon exists at many spatial scales, including intimate, personal, conversational, public and urban. The volume of an intimate arena is approximately half a meter in diameter. The most obvious example is an arena of two people whispering, which creates a domain with an SPL of 20 dB (BLESSER, Barry and Salter, Linda-Ruth, 2006). Less researched examples are the intimate spheres that form within highly noisy environments, such as speaking loudly at a nightclub or on a cliff during a strong gust of wind. The difference is that the threshold in the first example is entirely dependent on energy loss and the later arena shrinks because of high interference (TURNER, John and Pretlove, A.J., 1991). A normal conversation creates a ‘personal’ scale arena, approximately one meter in diameter, and the conversational arena may extend up to four meters. Similar to the intimate arena, these diameters contract in high-interference environments (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Spatial Perception and Navigation

Humans perceive sound binaurally through two receiving organs (i.e., ears) separated by the radius of the head. The ears receive two independent channels and convert spatial attributes into one spatial ‘image.’ The acoustic behaviour of adjacent objects and geometry result in aural navigational cues, such as time difference, amplitude and spectrum. Close surfaces in small spaces amplify low-frequency (heartbeats) and strengthen the resonance of high-frequency sounds.

Aural cues also support spatial navigation. For example, one experiment prompts blindfolded subjects to walk down a corridor. When subjects start at the centre, their ears detect similar tonal coloration reflections on both sides. If subjects deviate to one side, they detect a change in low-frequency tonal coloration in the ear corresponding to that side. Findings reveal that upon perceiving this change, subjects, consciously or subconsciously, correct their courses back toward the centre (BLESSER, Barry and Salter, Linda-Ruth, 2006).

 

A diagram illustrating navigational aspects. A Sonic Navigation cue in corridors

 

Normally, low-level sonic reflections occur in any space. The brain creates spatial mental maps that allow the individual to determine the location and direction of a sonic event. The decoding process distinguishes sonic reflections from direct sound waves. If the receiver is located between a wall and a sonic event, the ear closer to the surface detects tonal coloration and the other ear detects direct waves. A sonic shadow occurs if the sonic event and the receiver are on opposite sides of the wall. The type of sonic shadow depends on the physical aspects of the sound wave and the wall. For example, a low-frequency sound casts blurred and diffused shadows, while a high-frequency sound casts sharp shadows. Open door frames also create discernible acoustic shadows cues. In this instance, the listener registers two cues, the absence of tonal coloration at the gap in the surface and the sonic shadow that results from the sound beyond the opening (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Cue fidelity also changes in unnatural environments. Humans are not as adept in recognising directionality cues within high resonant, small or anechoic spaces. Anechoic spaces, considered ‘aurally dark,’ are typologies where sound waves do not reflect and are especially uncommon. Spaces can also be perceived as acoustically ‘opaque’ or ‘transparent’. An opaque space refers to one where the sounds inside are reflected back and no external sonic event permeates through the envelope. An acoustically transparent space allows the internal sonic events to propagate to the external environment while external sounds infiltrate the interior space (BLESSER, Barry and Salter, Linda-Ruth, 2006).

 A diagram comparing transparent and opaque acoustical spaces. [Left] Acoustically opaque. [Middle] Visually transparent but acoustically opaque. [Right] Acoustically transparent and visually opaque.

A diagram comparing transparent and opaque acoustical spaces. [Left] Acoustically opaque. [Middle] Visually transparent but acoustically opaque. [Right] Acoustically transparent and visually opaque.

[1] Acoustical mirrors or “listening ears” were used during World War I until they were replaced by radar technology. In fact, in the 1930’s there were attempts to establish a sonic connection between England and France across the channel.

Acoustic arenas have unusual configurations compared to other known physical spaces. For example, in a whispering gallery, one arena can exist in two non-contiguous physical areas, simultaneously [1]. If one sonic event dominates a room, the aural boundary may align with or
extend beyond its physical boundaries. Alternatively, the activities could create a matrix of aural arenas with interference zones that act as virtual cubicles within the physical boundaries (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Humans perceive sound binaurally through two receiving organs (i.e., ears) separated by the radius of the head. The ears receive two independent channels and convert spatial attributes into one spatial ‘image.’ The acoustic behaviour of adjacent objects and geometry result in aural navigational cues, such as time difference, amplitude and spectrum. Close surfaces in small spaces amplify low-frequency (heartbeats) and strengthen the resonance of high-frequency sounds.

Aural cues also support spatial navigation. For example, one experiment prompts blindfolded subjects to walk down a corridor. When subjects start at the centre, their ears detect similar tonal coloration reflections on both sides. If subjects deviate to one side, they detect a change in low-frequency tonal coloration in the ear corresponding to that side. Findings reveal that upon perceiving this change, subjects, consciously or subconsciously, correct their courses back toward the centre (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Urban Order & Public Space Design

A Brief in preparation for Acoustic Arenas & Urban Space Theory

The previous posts provided the reasoning for the study hypothesis and addressed the research question, “Is it possible to develop a public space design model derived from acoustical phenomena and aural spatial qualities?” The second research question is, “If so, how is the urban morphology of the public space reflected in aural spatial patterns, and what principles determine these formations?” To answer this question, the next research post briefly discusses the intersecting research fields; specifically, urban design and aural spatial awareness.

Urban design theory is a large and intricate field. This post discusses the aspects that pertain to the research topic, including urban order, growth morphology and network configuration. In the abstract, aural spatial awareness research considers how spaces are perceived aurally and determines what design manipulation techniques are needed during the design process. In the next post, an urban sonic discourse follows and draws parallels between urban and aural design elements, such as soundmarks and soundscapes. These urban sonic features are explained in terms of their significance in urban settings and symbiotic relationships with urban order, growth morphology and network patterns. 

Urban Order & Public Space Design

Cities are unique in that each has a recognisable ‘city shapeness’ and a general pattern that result from a common unit order that defines it as a city (MARSHALL, Stephen, 2008). The city emerges as the primary environment of the human species. One reoccurring research topic is the sonic character of a city, specifically, curbing noise pollution levels and restricting undesirable sound-level penetration in interior spaces.

Before discussing the uniqueness of the sonic pressure of a city and factors that define urban aural design, this post addresses the nature of cities to develop an understanding of structure and functional design. Modern cities have more complex soundscapes that are often planned features. Marshall (2008) argues that traditional urbanism functions better at the human scale and provides better public spaces for citizens to interact. This research examines historic traditional cities with pedestrian-friendly streets and public squares (plazas, piazzas, or courtyards) to examine receivers’ (i.e., humans) responses to the morphology and sonic events of the space.

Ancient city plans, such as those in nineteenth-century Europe and adapted ancient Roman cities are initially planned but growth patterns do not show any signs of pre-design. As a whole, these cities seem to have city shapeness or an identifiable urban morphology. This morphology is a result of the association between individual units. The complex aggregation of these units (streets and building blocks) creates urban public space patterns and networks (MARSHALL, Stephen, 2008). Conversely, traditional Islamic cities do not have formally institutionalised planning, which results in amorphic patterns of growth that emerge around built archetypes. Friday mosques, embedded in a framework of central markets fulfil institutional functions. No specific morphological growth pattern exists in Islamic cities; rather, they develop according to site constraints, community size, economic resources and building materials (BIANCA, Stefano, 2000).

Damascus, an ancient North African city, retains the inner morphological affinities of the earliest Arab cities. When appropriated, Damascus was planned per Roman traditional town-planning regulations with a strict grid layout and main axial roads. With the Islamic adaptation, the grid was no longer the governing factor of the morphology of public spaces or residential districts. The main roads started to secede into smaller pedestrian parallel paths around small market structures. Privacy became the deciding factor in creating a broken flow of successive hierarchal streets that ended in courtyards. This shift led to inward-oriented autonomous units that formed around courtyards. Research suggests that traditional communities centre on religious beliefs (Muslim, Christian, or any other) materialise their environments to reflect the individual perceptions of universal truth (BIANCA, Stefano, 2000). This definition is relevant to the current study in which sonic events originating from the foci of communities infiltrate private residential districts and define their sonic characters.

Design Theory

Designers across the spectrum of spatial scale tackle design problems by addressing how fundamental units work together; architectural elemental units include spatial components such as rooms and circulating corridors. Urban designers use similar components at a larger scale (building blocks and public urban spaces). 

Design units are the indivisible components that would lose functional integrity if fragmented. In other words, units are unable to exist independently; they only function as an aggregation of other urban units. For example, a room cannot function in isolation; rather, the composite of rooms acts as a subcomponent arranged in a determined order to form a building, and the building forms an urban unit. If the dimensions of one subcomponent (e.g., room) are multiplied the unit may act as self-sufficient (small building or cabin) (MARSHALL, Stephen, 2008).

 An adapted diagram of Sub-component Aggregation. (a) A sub-component can not be a stand-alone element (b) If a sub-component’s dimensions are increased it can act as a ’whole’. (c) A two-dimensional array of subcomponents assembling a complete component, with the ground as a common datum (d) A three-dimensional array of sub-component assembling a complete component (building) (e) A two-dimensional array, where sub-components are aggregated with intermittent ‘void’- (public space), moving into urban scale. (f) A three-dimensional array of sub-component, where subcomponents are aggregated with intermittent ‘void’ – against gravity Original Image Reference: (Marshall, Cities, Design & Evolution, 2008).

An adapted diagram of Sub-component Aggregation. (a) A sub-component can not be a stand-alone element (b) If a sub-component’s dimensions are increased it can act as a ’whole’. (c) A two-dimensional array of subcomponents assembling a complete component, with the ground as a common datum (d) A three-dimensional array of sub-component assembling a complete component (building) (e) A two-dimensional array, where sub-components are aggregated with intermittent ‘void’- (public space), moving into urban scale. (f) A three-dimensional array of sub-component, where subcomponents are aggregated with intermittent ‘void’ – against gravity Original Image Reference: (Marshall, Cities, Design & Evolution, 2008).

Buildings are designed around interior artificial environments designed at a human scale, which is determined by the size of the average human in an upright position. The form of interior spaces is not a coffin-like box influenced by this defining measurable scale and number of humans. Rather, form is derived from the psychological and intellectual characters of inhabiting users and social activities. When the same subcomponent is repeated in a straightforward two-dimensional or complex three-dimensional array, a unit structure, such as a city block or building, evolves at a larger scale. Even though the number of atomic units increases, the overall cell maintains a state of ‘wholeness,’ as with a building. Similarly, buildings assembled in two-dimensional arrangements become subcomponents of a more complex ‘whole’ or urban fabric (MARSHALL, Stephen, 2008).

When the subcomponents become part of the urban fabric, the system is transferred from a building scale to an urban scale. The two-dimensional aggregation of the building blocks generates an indivisible unit (void or streets) without which the nature of the new unit could not exist. If buildings are constructed adjacently, without streets and public spaces, the result is a larger building block, not an urban fabric. The size and form of a building or urban fabric is a derivation of the size, number and aggregation system of the subcomponents (MARSHALL, Stephen, 2008). Theoretically, a three-dimensional version of this solid-void system is possible; however, gravitational forces render it impractical. This discussion does not consider this impractically, but it is referenced in the following section with a discussion on aural design. Aural spatial units follow the same logic in which the activity held and the number of users in the domain determines the unseen boundaries.

Order and Growth

Prior to modern communication and transportation growth factors, the sonic character of a city was coherent. Consistent indications infer the effect of sound on the morphological growth of old townships and the formation of city edges. The strongest defining sound customarily originated from the centre of the town (BLESSER, Barry and Salter, Linda-Ruth, 2006). Therefore, it is pivotal to understand the basic concept and defining factors of urban growth.

Urban growth is ‘human-shaped’ and based on a social logic and theoretical order of building blocks and streets. A society is a group of humans who vary in gender, generation, and economic statuses and co-exist by abiding by a contract. Such agreement states that all parties (everyone in society) agree to limit some of their freedoms (MARSHALL, Stephen, 2008). Despite the differences in regional climates, cultures, technologies and economies, urban forms are diversely evident over space and time.

Urban order goes beyond the abstract unit typologies of buildings and public voids; it is also defined by users’ purposes (i.e., programmatic use). Social groups (communities/neighbourhoods) and social units (family/workplace) are units that contribute to urban order, form and growth. Similar to the physical spatial units of cities, these units are the building blocks of society that have hierarchical structure. Buildings form around the social organisation and define the relation between social and spatial structures. For example, the form of a Greek amphitheatre reflects the relationship between the performers and the audience. Because of this relationship, buildings grow and become more complex as social units increase in size and complexity.

Various practical and social factors can prevent indefinite growth (MARSHALL, Stephen, 2008). Cities are like living organisms; larger animals have different forms compared to smaller ones (STEADMAN, Philip, 2008). Unlike a building, city growth morphology is not only a monolithic aggregation of buildings; it grows as a textured fabric. As the system grows beyond sustainability, the resulting strain forces the settlement to become a larger social container or a city with distinct urban patches. In turn, urban patches (districts) become aggregating subunits of a city that form around social groups (MARSHALL, Stephen, 2008).

Concentric city growth is the most frequent morphology in which inner centralised higher functions are surrounded by lower and newer ones. This typically unplanned tradition is found in the irregular aggregation of street pattern shapes, which occur at different lengths and angles. Traditional cities implement a planned systematic order at the urban fabric scale. The corresponding fundamental units demonstrate a correlated pattern to each other, as they do to the whole city. The social structure of the city follows a characteristic, rather than systematic, order. Areas inhabited by similar social groups (e.g., ethnic backgrounds or economic status) are directly identified as communities or neighbourhoods. Thresholds between these neighbourhoods become blurred and separate urban patches with different morphological characteristics, which are the direct result of the social groups inhabiting these patches (MARSHALL, Stephen, 2008).

 An adapted diagram of urban order. [Top] Systematic order: a set of objects, or units, have the same relationship with respect to each other. [Bottom] Characteristic order: a rough type of order that typically is found in un-planned order. Original Image Reference: (Marshall, Cities, Design & Evolution, 2008)

An adapted diagram of urban order. [Top] Systematic order: a set of objects, or units, have the same relationship with respect to each other. [Bottom] Characteristic order: a rough type of order that typically is found in un-planned order. Original Image Reference: (Marshall, Cities, Design & Evolution, 2008)

Networking

Studying street networks and patterns provides an understanding of urban growth and morphology (MARSHALL, Stephen, 2005). Structurally, a city is an organisational network similar to the internet. The structure differs from other organisational networks in that it has a common planar datum that grounds it into a two-dimensional plane. Street and urban space networks are arguably a contributing factor to better city design. Space networks are system units or single lines that create the signature skeletal structure of the city. Thus, the network structure depends on the contiguity of these linear elements (MARSHALL, Stephen, 2008).

Historically, central places and main routes illustrate a reverse relation to modern planned cities. Markets, plazas and squares are urban circulation cores, and the intensity of the circulation dissipates outward from the foci. Movement is the main programmatic function of spaces created between city blocks. Spatial organization and the morphology of these ‘movement spaces’ is a direct result of the information flow, geometry and connectivity topology (MARSHALL, Stephen, 2005).

 An abstract diagram of historic settlement structure. The market square holds a central position, and the circulation intensity attenuates further away from the core. The routes closer to periphery of the town are of relatively lower hierarchical levels. Original Image Reference: (Marshall, Streets and Patterns, 2005)

An abstract diagram of historic settlement structure. The market square holds a central position, and the circulation intensity attenuates further away from the core. The routes closer to periphery of the town are of relatively lower hierarchical levels. Original Image Reference: (Marshall, Streets and Patterns, 2005)

Characteristically, urban networks are arranged in a hierarchical fractal structure, and principal arterial streets are connected strategically to form a single network. Lower-order streets feed off this system but are not necessarily totally connected (MARSHALL, Stephen, 2005). The characteristic connectivity of streets highlights these elements as the components that create the urban network structure. Although this structure may appear irregular, it is a systematic order known as urban syntax (MARSHALL, Stephen, 2008).

Urban design research designates various classifications and descriptors for urban network patterns. Some descriptors refer to street configurations or intersection topologies, while others refer to the alignment of streets and urban spaces. Marshall (2005) argues that recognised sets depend on the target of study [1]. He also points out that urban morphology classification requires emphasising the geometry of formed blocks. The case studies considered in this research warrant discussing Marshall’s A-type (Altstadt) network topology, which is typical of old walled cities with angular routes oriented in various directions. Often, this pattern topology is seen as the core of the city, and rudimentarily grows radially outward. As a result, the configuration of the urban network may have high connectivity, but it is characteristically impermeable (MARSHALL, Stephen, 2005).

 An adapted diagram A-Type [Altstadt] street pattern. Is typical of the core area of old cities. The angularity of routes, oriented in a variety of directions, generates a rudimentary radially, where such a pattern is located at the core of a settlement. [Top-Left] Mixture of configuration properties (Tand X-junctions, some cul-de-sac; moderate connectivity. [Middl-Left] Irregular, fine scale angular, streets mostly short or crooked, varying in width, going in all directions. [Bottom-Left] Composition of the built areas [Right] Types of constitutional structure [conjoint] arterial without access constraint. Original Image Reference: (Marshall, Streets and Patterns, 2005)

An adapted diagram A-Type [Altstadt] street pattern. Is typical of the core area of old cities. The angularity of routes, oriented in a variety of directions, generates a rudimentary radially, where such a pattern is located at the core of a settlement. [Top-Left] Mixture of configuration properties (Tand X-junctions, some cul-de-sac; moderate connectivity. [Middl-Left] Irregular, fine scale angular, streets mostly short or crooked, varying in width, going in all directions. [Bottom-Left] Composition of the built areas [Right] Types of constitutional structure [conjoint] arterial without access constraint. Original Image Reference: (Marshall, Streets and Patterns, 2005)

 An adapted diagram of permeability and connectivity. [Left] Greater permeability [Middle] Less permeability [Right] Both have the same connectivity. Original Image Reference: (Marshall, Streets and Patterns, 2005)

An adapted diagram of permeability and connectivity. [Left] Greater permeability [Middle] Less permeability [Right] Both have the same connectivity. Original Image Reference: (Marshall, Streets and Patterns, 2005)

Public Spaces & Interstitial Spaces

Only when both streets and buildings exist can a city substantiate. Streets and public spaces are not just the void between buildings; they are urban units and are a part of the urban social fabric. Public spaces are designed as void volume that is circumscribed by the vertical elements of a city. In general, cities have significant vertical dimensions; however, the ‘urban signature’ of a city is distinguished along a datum surface. Thus, city shapeness is better represented as a two-dimensional organisational plan. A typical city plan has a set of isolated similar areas (land parcels) surrounded by linear interdependent and interconnected elements (streets systems). This order is known as archipelagos, a system illustrated in the continents surrounded by oceans. The contiguity of street systems regulates urban order, and private plots connect directly to this contiguous network. Buildings located on these private plots house social groups comprised of various types of social units. The route network is a conjugating tissue of public spaces between these social groups (MARSHALL, Stephen, 2008).

 An adapted diagram of connectivity and order. [Top-Left] ‘Archipelago’ example, earth map. [Top-Right] Navigating the ‘archipelago’, All ports of call are connected by the continuum of public space. [Bottom-Left] Linear urban space, street. [Bottom-Right] Linear connectivity of urban space. Original Image Reference: (Marshall, Cities, Design & Evolution, 2008) (Marshall, Streets and Patterns, 2005)

An adapted diagram of connectivity and order. [Top-Left] ‘Archipelago’ example, earth map. [Top-Right] Navigating the ‘archipelago’, All ports of call are connected by the continuum of public space. [Bottom-Left] Linear urban space, street. [Bottom-Right] Linear connectivity of urban space. Original Image Reference: (Marshall, Cities, Design & Evolution, 2008) (Marshall, Streets and Patterns, 2005)

Historically, public spaces have social character. For example, centralised squares, market places and main streets have a ‘people’s place’ role that is rich with diverse and complex programmatic responses to the social fabric. One can consider the visual morphology of a space as an ‘outdoor room’ with a direct relationship to the encircling buildings. Social asymmetries exist within social groups (the government and the governed), and they determine the hierarchical path of information flow (e.g., where and to whom certain information circulates). With advances in communication and transportation technologies, this social hierarchy may exist in a non-physical state, and the nature of the hierarchy and information flow trajectory define urban morphology (MARSHALL, Stephen, 2008).

Subtle social complexities and proximities result in the interpretation of private and public spaces. A public domain implies that it is an uncontrolled all-inclusive space. ‘Strangers’ do not need to behave according to certain rules other than popular social conventions. Public spaces are inclusive distinct foci where different social groups interact and communicate. The private-public order is a key social construct that manifests across the urban fabric and the programmatic use of the domain determines the topological order that forms the public space. Thus, a domain can be designed to encompass more than one or to be mutually exclusive.

The topology of a recognised public space is an all-inclusive space with segregated exclusive
subdomains. These subdomains have direct access to the all-inclusive space, which creates an
archipelago order. Nested topology is a more complex hierarchical configuration with a public-private gradient of residual inclusive domains that is determined by the programmatic use of the public space. Specifically, the design manipulates the physical attributes of the space to establish a hierarchy by employing subdividing barriers that do not need to be visually barring. For example, roping off a café sitting area with knee-high poles is sufficient to create an exclusive domain for patrons. A change in ground level is also a spatial filter. For example, in an assembly area, a stage or platform creates a social filter between the performers and the audience (MARSHALL, Stephen, 2008).

 An adapted diagram of private and public Domains. [Top-Left] Public all inclusive public space. [Top-Right] 2 exclusively private domains. [Bottom-Left] ‘archipelago’ ordered private sub-domains with direct access to an all-encompassing public space. [Bottom -Right] Public-private gradient: Nested public spaces with caressingly exclusive restrictions. Original Image Reference: (Marshall, Cities, Design & Evolution, 2008)

An adapted diagram of private and public Domains. [Top-Left] Public all inclusive public space. [Top-Right] 2 exclusively private domains. [Bottom-Left] ‘archipelago’ ordered private sub-domains with direct access to an all-encompassing public space. [Bottom -Right] Public-private gradient: Nested public spaces with caressingly exclusive restrictions. Original Image Reference: (Marshall, Cities, Design & Evolution, 2008)

[1] Stephen Marshall developed a network typology that reflects typical street patterns that are encountered in different kinds of urban analysis, namely ABCD typology. (A-type/Altstadt , B-type/Bilateral, C-type/conjoint, and D-type/Distributary) (MARSHALL, Stephen, 2005)

Auditory Sense Manipulation in Spatial Design

This research does not presume that architectural and urban design never use sound, as ample research and design precedents apply the science of acoustics. Rather, design methods that address sound as a primary parameter are employed in specialised buildings such as assembly spaces (concert halls, sound studios, or lecture halls), not as the norm for general spaces. 

In reference to neurobiological research, successful acoustical techniques consider the  physiological effect of sound. Classic Greeks successfully built the Epidaurus Amphitheatre in the fourth century B.C.; yet, through multiple attempts, they were still unable to reproduce the methods that generate the unique acoustic qualities of the amphitheatre. Recent ultrasonic investigations reveal the significant property that distinguishes this space. Discussion is included on the aurally honed perception techniques that the ancient Mayan civilization used to construct a temple using complex geometry and material morphology to convey a particular narrative.

Concert halls are a well-established typology of buildings developed continually since the classical Greek amphitheatres. This post reviews the Segerstrom Performance Hall, designed by Charles Lawrence in 1983, and the McDermott Concert Hall, designed by I. M. Pei in 1989. These halls fuse acoustical strategies that are still applied and revised. The issues discussed here have significant implications on space and influence fundamental architectural characteristics. Among these features is room volume, ceiling height, longitudinal and cross-sectional spans and surface materials (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

In conclusion, there are design projects by two modern composers, architects and engineers, Iannis Xenakis and Bill Fontana. The significance of this discussion is the generational gap and opposing design approaches of these two designers. Xenakis designed buildings to compose a series of specific sonic events. In contrast, Fontana harnesses the sonic events that originate from the environment (or building). For both designers’ works, the primary objective is to broadcast a distinct narrative through multi-disciplinary research and methods, such as bridging architecture with art, mathematics, and music. These designers illustrate a firm understanding of how the aural design of a building affects users, and they use that knowledge to their benefit.

Historical Aural Design

An Image of the Epidaurus Theatre. Image by Andreas Trepte

Historically, buildings that successfully employ acoustic manipulation techniques incorporate material and geometrical design components. Most acoustic design literature refers to the Mayan Chechen Itza temple and the ancient Greek Epidaurus Amphitheatre. Chechen Itza and its acoustic anomalies speak to the ancient Mayan’s political, religious and cultural objectives. The temple builders lived in the Cloud Forests where auditory stimuli were the primary signals for understanding their surroundings. In the forest, a person can hear objects beyond his or her visual horizon (LUBMAN, David, 1998). 

An analytic model of the Epidaurus acoustics. [Top] 3D model of the lower cavea of Epidaurus. [Bottom - Left] Measured frequency responses. [Bottom - Right] Frequency responses of simulation results. The model of Epidaurus used in the simulations has only the lower cavea consisting of 31 seat rows. Source position S1 is in the centre of orchestra and sources S2, S3, and S4 are on the stage. Frequency responses (smoothed at 1/3 octave bands) at receiver positions 1 to 31 on Line L from source position S4 on the stage. The average frequency response of male speech is shown for reference. Four responses are computed within a time window from the initial direct sound up to 20, 50, and 1000 ms. Images and caption Reference: (AALTO UNIVERSITY SCHOOL OF SCIENCE, DEPARTMENT OF MEDIA TECHNOLOGY, 2013).

Likewise, the Epidaurus illustrates the ancient Greeks’ scientific and technological advancements. These historic buildings are good examples of filtering certain frequencies via material use and geometrical manipulations to create narratives. The well-preserved Hellenistic theatre of Epidaurus on the Peloponnese in Greece is famed for its acoustical character. Performance sounds issuing from the centre of the theatre reach the outer seats with minimal intensity loss (DECLERCQA, Nico F and Dekeyser, Cindy S A, 2007). The ancient Greeks’ endeavours to replicate the features of this space were not successful, and much dispute exists concerning the primary factors of seating slope, direction of the prominent wind, geometric surface details, and the limestone materials used (MCRAINEY, Megan, 2009). Researchers recently found the geometric and material formula that filters and amplifies low-speech frequencies, simultaneously (SHANKLAND, Robert S, 1973).

An image of Chichén Itzá - Yucatan, Mexico. Pre-Columbian Mayan Architecture. Image by Bmamlin - Clapping in specific parts if the courtyard triggers chirp-like flutter echoes.

Declercq and Dekeyser (2007) conducted a non-invasive ultrasonic wave test on the amphitheatre. The findings reveal that the back seats (the cavea) backscatter the sound to the audience, which creates unimpeded indirect sound waves. The audience receives these indirect waves in a moderately short time after the direct waves originate from the stage (DECLERCQA, Nico F and Dekeyser, Cindy S A, 2007). The simultaneous reception of the direct and indirect waves reflecting off a hard material nearly fuses both sound waves into one amplified sound (LOKKI, Tapio et al., 2011). This event produces loud and high speech intelligibility (AALTO UNIVERSITY SCHOOL OF SCIENCE, DEPARTMENT OF MEDIA
TECHNOLOGY, 2013).

A signal comparison between the Quetzal bird and the resulting reflection. [Top-Left] The actual sound of a real Quetzal bird in the forest. [Top-Right] Numerical echo corresponding with an incident numerical handclap with frequencies higher than 10 240 Hz neglected. [Bottom] It is seen that the ground has no influence on the presence or absence of the frequency bands. The graphs describes precise diffraction simulations of physical effects that cause the formation of the chirp echo. Numerical simulations show that the echo shows a strong dependence on the kind of incident sound. Simulations are performed for a real handclap. The numerical signal coincide with the experimentally measured frequency bands. This proves that the lower two frequency bands in the experiments are mainly caused by the nature of the handclap and not by the diffraction process. Figures and caption Reference: (DECLERCQ, Nico F and Degrieck, Joris, 2004).

Declercq and Dekeyser’s (2007) ultrasonic tests and numeric simulations infer that the corrugated limestone steps serve as modern-day rigid acoustic padding. The seats function as a high-pass filter to amplify high frequencies and cross over low frequencies (AALTO UNIVERSITY SCHOOL OF SCIENCE, DEPARTMENT OF MEDIA TECHNOLOGY, 2013). This phenomenon varies slightly depending on the periodicity of the seat rows (DECLERCQA, Nico F and Dekeyser, Cindy S A, 2007). The limestone reflects frequencies above 500 Hz and retains those lower than this threshold, which dissipates the audience’s minute coughs and whispers, while the filtering material absorbs the low- frequency waves propagating from the stage. Despite these variances in sound, through cognitive auditory grouping, the audience perceives the performance as a continuous, uninterrupted event (i.e., virtual pitch phenomenon) (ANITEI, Stefan, 2007).

Vowels carry the strongest power of harmonic signals and are the most informative parts of a syllable. All vowels range between 300 and 3000 Hz, which is mostly above the amplification frequency threshold in Epidaurus. If a performer broadcasts from the stage, the backscattering and early reflections amplify the enunciated vowels (AALTO UNIVERSITY SCHOOL OF SCIENCE, DEPARTMENT OF MEDIA TECHNOLOGY, 2013). Through experience or integral visual signals, the brain perceives the delivered speech as uninterrupted legible words (LEVITIN, Daniel J, 2007).

The literature confirms that, like the Greeks, the ancient Mayan civilization in Central America possessed a firm grasp of mathematics, astronomy and social organisation. Unlike the ancient Greeks, the Mayans did not leave written evidence notating their deliberate recognition of acoustical attributes of the structures they built. It has been conjectured that these acoustical attributes are the result of their physical environment and the learnt auditory associations they gained by living in it (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Among these seemingly acoustically designed buildings is the Pyramid of Kukulkan at Chichen Itza, in Mexico. Observers seated on the lowest steps of the pyramid report hearing the sound of raindrops as other people climb the stairs (DECLERCQ, Nico F and Degrieck, Joris, 2004). Acoustic consultant and scientist, David Lubman, discovered that when illuminated by the sound of clapping hands, the staircase of the pyramid produces chirp-like echoes. He dubs this phenomenon as ‘flutter echoes’ (LUBMAN, David, 2006). The resulting flutter echo resembles the sound of the Mayan’s sacred bird and the temple deity, the resplendent Quetzal (BLESSER, Barry and Salter, Linda-Ruth, 2006).

The presence of long stairs that face open courts in other Mayan sites implies that this design feature was purposeful. In traditional western architecture, flutter echoes are considered defects, yet, the Mayans utilised this design to convey a significantly perceptual cognitive narrative. The average flutter frequency in the Mayan Great Ball Courts is 4 Hz, which corresponds to the maximum human sensitivity for auditory warning signals, namely “fluctuation strength.” Reportedly, these echoes resemble the growl of a jaguar or the rattle of a rattlesnake [1] (LUBMAN, David, 2006).

Concert Halls

The Segerstrom Performance Hall and McDermott Concert Hall were built at the time computational simulation was established. Concert halls are interior spaces intended for absolute acoustical purposes, and they employ technical methods that do not provide room for subjective interpretation. Continuous unobstructed sight-lines are a firm non-negotiable parameter that determines spatial geometry. The prime design purpose for such spaces is to configure architectural features to provide high-quality acoustics. These spaces are multi-purpose halls where a range of performance types are conducted (drama, opera, ballet and orchestra concerts), and each hall applies different strategies of acoustic principles (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

The Segerstrom Performing Hall, designed by Charles Lawrence in 1983, is a multi-purpose room with a volume of 27,800 m3 that seats 3000 persons. The difficulty here is that the space is required to achieve a level of acoustic quality comparable to a smaller rectangular-shaped room within a much larger space. The occupancy capacity defines the shape of the room—fan-shaped plan—that accommodates the required capacity and sustains uninterrupted sight-lines. This design is based on lateral reflections, which support indirect sound waves that reflect and arrive at the listener’s ears from the side rather than from the back (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

An interior image of The Segerstrom Performing Hall The image shows how the designer breaks up the interior space to create more surfaces that provide lateral reflections. Image Reference: (TBP/ARCHITECTURE, INC., 2014)

Lateral reflections manipulate the aural perception of proximity to create enveloping, intimate and spacious sensations (LEVITIN, Daniel J, 2007). Research on spatial impression indicates that excessively strong lateral reflections may cause confusion and image shift, and the audience may respond to the indirect sound involuntarily. Thus, the lateral reflection technique is ineffective in large spaces. To compensate, designers subdivide the space and vertically stagger smaller spaces to create supplementary sidewalls that provide lateral reflections. This configuration maintains a sense of intimacy and provides adequate sight-lines (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

Two Sample Plans of The Segerstrom Performing Hall [Top] Main Level [Bottom] Third Level Original plans by Jerald R. Hyde Plans Reference: (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

Reflecting and defusing ceiling panels hover over the space close to the audience to provide shorter sound reflections and enhance clarity and loudness. These panels are focused toward the centre portion of the subspaces to guarantee lateral reflection coverage. Gaps between the panels allow some sound energy to travel above them to yield longer reverberation times (2.3 seconds) and create a juxtaposition of short lateral reflections. This combination creates balance between clarity and reverberation—the ultimate goal of any assembly hall configuration. Adjustable curtains positioned in the space between the ceiling and suspended panels may be lowered or elevated to control reverberation for different types of performances (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

An Interior image of Meyerson- McDermott Concert Hall. The design employs narrow balconies along the back and side walls. The stage is covered by an operable panel to adjust reverberation time and reflection angles. Image Reference: (LONG, Brandon, 2010)

The McDermott Concert Hall was designed and completed in 1989 by I. M. Pei and Partners, Inc. in coordination with the acoustical consultancy office, Artec Consultants, Inc. Its occupant capacity is 2065 persons and its total volume is 27,800 m2. Principal acoustic consultant, Russell Johnson, was well known for using computational modelling and acoustic simulation in his design study—a novelty at the time. Many historical precedents, including seventeenth-century European opera houses, influenced the design of the McDermott Concert Hall. Among these borrowed historic features is the stacking of several narrow balconies along the edges of the space that adopt a narrow shoebox form and use heavy highly reflective materials on non-uniform surfaces [Refer to: Figure 2. 20]. The use of dense material finishes eliminates the loss of low-frequency reflections.

The overall plan of Meyerson-McDermott Concert Hall. Original plans by Artec, Inc. Plans Reference: (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

The space design also incorporates modern architectural and acoustical features, some of which were developed specifically for this space. For example, ‘reverberation chambers,’ large areas surrounding the upper portion of the room, are encased in concrete walls. These areas are segregated from the main hall by operable panels that can be opened and adjusted to assert the amount of reverberation needed for each type of performance. The adjustability of reverberation and its time enables the operator to maintain clarity, which is achieved by balancing the rebounding indirect sound waves with the warm tail of the reverberation effect (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

Similar to the Segerstrom Performing Hall, a system of multi-layered screens can be withdrawn into storage spaces along the side walls. These screens are used to minimise reverberation when speech is the primary activity. The design uses a feature that helps propagate low-frequency sounds from the stage toward the audience. A segmented five-layer laminated wood canopy hangs above the stage and is motor-operated to change the angle of inclination. The canopy and reverberation chambers complement each other. If the canopy is raised, low-frequency waves bounce into the reverberation room to enhance sound fidelity. The short reflection time of the canopy increases orchestra members’ abilities to hear each other in time and to gain an accurate sense of their own instruments’ sounds (SIEBEIN, Gary W and Kinzey Jr, Bertram Y, 1999).

Modern Design

Iannis Xenakis, a prominent modern architect, addressed sound and space. As a musician, mathematician, and architect, he formalised his knowledge to manipulate the acoustic perception of his composed spaces (XENAKIS, Iannis, 1997). Xenakis employed multiple parameters to accomplish sonic filtration. Two of these parameters are well-known aspects of the previously cited examples, material and geometry (MATOSSIAN, Nouritza, 2005). Xenakis predated the digital and parametric design boom. His mathematical training enabled him to apply computational and algorithmic principles to filter sound into his architectural practice. This process adopts datasets based on physics, environmental trajectories and material use.

The method that Xenakis used to formalise music to a structural design. [Top] Glassandi analysis [Bottom] Phillips Pavilion wireframe structure. Xenakis translated the tones and durations to a vector
diagram, that then was used as structural vectors to create the pavilion’s roof structure. The image shows the relationship between diagrams of the coda to Xenakis’ piece Metastasis, 1955. Designed for Expo ‘58 in Brussels World Fair Designer Iannis Xenakis Image Reference: (PROBZ, DESIGN, 2012)

The Philips Pavilion is one of Xenakis’ recognised projects, and was designed while working for Le Corbusier in 1956. The pavilion design intended to highlight the technology that Philips (the company) had to offer. Xenakis’ diverse talents enabled him to develop various features of this project. He wrote the focal sonic event of the project, ‘Poème Électronique’[2], an eight-minute interlude that synthesises sound and light using Philips’ technology. His research aimed to spatialise the pavilion aurally and was the foundation for developing his consequential polytope investigation[3].

Hyperbolic Paraboloid forms became Xenakis’ specialty. He developed this geometrical technique during this project to eliminate sonic dead spots, or acoustic shadows.’ Through trial-and-error, he succeeded in pushing the use of concrete to its limits and created a pioneering attempt of free-form geometry. Xenakis’ hyperbolic paraboloid investigations were unconventional at the time. For example, he converted the glissandi structure in ‘Poème Électronique’ into two-dimensional vectors mapped out in time. Without the aid of high-computing machines, the exercise facilitated the adaptation of geometrical and vector calculations to structural vectors to create the complex hyperbolic paraboloid geometry (XENAKIS, Iannis, 1997).

An image of Couvent de St. Maria la Tourette - West Façade Xenakis‘ famous ‘Undulating glass panes’ that is based on his earlier study ‘the Modular.’
Image Reference: (EMDEN, Cemal, 2012)

Among Xenakis’ prominent aural designs, Couvent de St. Maria la Tourette and Cité de la Musique employ innovative aural design features. Couvent de St. Maria la Tourette was Xenakis’ first project after holding the position of project architect with Le Corbusier. Xenakis invented his renowned ‘undulating glass panes’ architectural feature for this project for the west façade based on his earlier study The Modular. The Modular is a complex proportional scale formulated to merge human dimension scale with the Golden Mean and the Fibonacci sequence. This process formed his musical solution; double frieze windows of varying widths that create shifting rhythms (LOVELACE, Carey, 2010). When high-speed winds pass over the panes, they generate a harmonic ambient tune (MATOSSIAN, Nouritza, 2005). Xenakis developed related concepts concurrently in his musical piece Metastaseis (1953 1954), which formalises polyrhythms based on superposed stochastic calculations. Almost every design Le Corbusier’s studio produced after 1955 incorporates this feature (XENAKIS,
Iannis, 1997).

Cité de la Musique, in Paris, is a natural evolution of Xenakis’ work in which all of his musical, architectural and engineering research culminates. This piece was his entry for a competition held in 1984. While the piece was not selected to be built, it is crucial to consider it along with his scrupulous design thought process of the auditorium ‘Jewel Box of Sound’ (MATOSSIAN, Nouritza, 2005). The design premise considers the auditorium itself as a musical instrument. The generated form became an ellipse-shaped space covered with an inverted tulip-shaped hyperbolic reinforced concrete roof. He also incorporated his other aural design techniques and research, including undulant glass panes (XENAKIS, Iannis, 1997).

Animage of Bill Fontana’s Sonic Shadows at SFMOMA. Photo By Don Ross Image Reference: (OZLER, Levent, 2010)

Among Bill Fontana’s recently published work, ‘Sonic Shadow’ incorporates ambient live sounds generated by a building. The work is a sound installation at the San Francisco Museum of Modern Art (SFMOMA) that collects sounds caused by forces exerted in a skylight structure and the pedestrian bridge located in the atrium. The design transmutes these architectural and structural elements into musical instruments. The skylight radiates ecological and urban sounds, whereas the bridge resonates with the visitors’ steps. Fontana’s work is primarily technical; he does not modify the structure, he only enables visitors to hear it by capturing the vibrations of the building using a network of high-calibre accelerometers and projecting the signals using ultrasonic carrier speakers that possess a directional throw capacity to target different walls. The projected waves then reflect back to the visitors’ ears. Targeting the sound subdivides the atrium space into distinct aural subspaces visitors can hear different sonic events at different locations (DUFF, Simon, 2011).

Modern composers, such as Xenakis and Fontana, use techniques that consider location as an animated design element and a variable parameter. The deliberate sequencing spatial attributes, together with sonic properties, generate a reciprocal trajectory of sound or space. This transient property defines spaces as a musical dimension. The contiguous composition ‘Poème Électronique’ and the design of the Phillips Pavilion became prototypes of spatial art. The interior space and the visual and aural compositions are superimposed entirely to produce a whole design that is stronger than the sum of its parts. Fontana’s work fuses soundscape music and acoustic ecology within a space to become a living system with natural sounds and acoustics. The use of various speakers increases the spatial design potentialities and presents them as ‘aural architects’ (BLESSER, Barry and Salter, Linda-Ruth, 2006).

[1] Rattlesnake rattles are usually higher in frequency (LUBMAN, David, 2006)

[2] Poème électronique “Electronic Poem” is a piece of electronic music by composer Edgard Varèse, written for the Philips Pavilion at the 1958 Brussels World’s Fair (Poème électronique).
[3] In elementary geometry, a polytope is a geometric object with flat sides, which exists in any general number of dimensions. A polygon is a polytope in two dimensions and a polyhedron in three dimensions

Musicology Concepts and Spatial Awareness

As neither the enjoyment nor the capacity of producing musical notes are faculties of the least direct use to man in reference to his ordinary habits of life, they must be ranked amongst the most mysterious with which he is endowed. They are present, though in a very rude and as it appears latent condition, in men of all races, even the most savage.
— Charles Darwin~1871

A Graphic by Iannis Xenakis Pithoprakta (1955-56). Formalising musical note pitch and duration into vectoral algorithms Image Reference: (SOLOMOS, Makis, 2013) (MATOSSIAN, Nouritza, 2005).

Typically, sound research is linked closely to other sciences such as musicology, the science of music.Although a sentimental notion exists that music is a product of numinous inspiration, scientists refer to mathematics and biology to understand the human response to music. Many musicology paradigms align with the hypothesis of aural design discourse. Consequently, these theories can be extrapolated for the intent of this study, which is to ‘organised sound’ in urban space [1].This section briefly discusses the evolution of music and its relation to human cognitive and social behaviours and considers research on the effect of music on biological and physiological responses.

While no dispute exists over the evolutionary purpose of the auditory sense and language, there is much controversy on whether the existence of music (and music making) has an evolutionary explanation. Scientists on both sides of the argument refer to Darwin’s phrase ‘survival of the fittest’ and his two-volume publication The Descent of Man to make their opposing points. Cosmologist, John Barrow, states that music plays no role in the survival of a species. Psychologist, Dan Sperber, goes so far to call music “an evolutionary parasite.” Sperber believes that music evolved in preparation of language.

Cognitive scientist and evolutionary psychologist, Steven Pinker, agrees with Sperber, and states that music is merely an evolutionary by-product of language. Pinker asserts that listening to music is a pleasure-seeking behaviour that circumvents the original evolutionary purpose and directly taps into a reward system (LEVITIN, Daniel J, 2007). Ball, a science writer, takes a neutral position and explains that the brain dedicates several regions to handle music, which implies that music serves an adaptive function (BALL, Phillip, 2011).

Levitin cites Darwin’s sexual selection concept and declares that music has an evolutionary purpose. Like other species, humans create organised sound as an exhibitionist behaviour. This determining reproductive phenomenon is associated with dexterity, coordination, determination, and good hearing genes. Levitin employs Levitin employs Sperber’s rationale by which the cognitive ability to process complex sound patterns that vary in pitch and duration evolved in pre-linguistic humans and prepared humans for speech communication (LEVITIN, Daniel J, 2007).

As social animals, humans use music to encourage feelings of unity and synchrony and to develop social habits of coordination and cooperation (LEVITIN, Daniel J, 2007). According to Levitin, this idea aligns with Blesser and Salter’s statement that people inhabiting the same area and subjected to the same sonic event (e.g., church bells) develop a sense of citizenship to that region. They introduce this concept as soundmarks (BLESSER, Barry and Salter, Linda-Ruth, 2006).

Sound Physiological Response

Grouping Coordination and Association

Following the description of biological and neurological processes, musicology research is discussed  to clarify the indicated synaptic processes and sound associations that formulate programmable music and chart spatial characteristics. Psychological and physiological sound nomenclature and perceptual influences are presented here. The acquired facts are extrapolated to inform the hypothesis of aural urban design. The focus here is the musicology subdomain of perceptual-cognition, which covers the physiological effects of sound and the communicative function of speech. The highly subjective matter of emotional response is not a concern of this study.

The terms defined here (pitch, rhythm and loudness) are more subjective than are their mathematical counterparts. Physiological, psychological and psychophysical studies use these terms to investigate the neurological and biological effects of sound. Psychophysicists reveal that these properties are separable parameters; one may alternate while the others remain constant. The contrast between ambient sound and music is the administration of and the correlation between these properties (LEVITIN, Daniel J, 2007).

Pitch

A Sample Range of mean frequency of various objects. Musical instruments, human vocals, urban sounds, and the corresponding notes on a standard 88 note piano. Diagram set on a frequency logarithmic scale. (Note: The infrasonic and ultrasonic notations are reversed. Please return to the post for updated graphic soon)

While the expression ‘Pitch’ may be confused with frequency, pitch is a purely psychological subjective construct that denotes the result of a sequence of cerebral functions in response to a frequency. Unlike any other sound attribute, the mind directly identifies pitch through the tonotopic-mapped basilar membrane and primary auditory cortex. The frequency selective configuration infers that pitch interpretation is the most significant perceptual factor (LEVITIN,
Daniel J, 2007). Studies indicate that the neural response to pitch is isomorphic. Magnetic resonance imaging (MRI) scans of subjects listening to music reveal that brain waves and the apprehended music are approximately identical (LEVITIN, Daniel J, 2013).

Pitch is the perception of the frequency of a particular tone [2] in relation to its position on the musical scale [3], on which C-sharp (or Middle C) is the mid-point (LEVITIN, Daniel J, 2007). The perceived pitch increases as the frequency of the transmitted wave (e.g., from a violin string) increases. Pitch is a mental image that results from a series of mechanical and neurochemical events triggered by sound vibrations that reach and oscillate the eardrum.

While a sound wave has a particular frequency, it has a pitch only when perceived (LEVITIN, Daniel J, 2007). A typical hearing adult can detect a spectrum of pitches that corresponds to a frequency range of 20Hz to 20 kHz [4]. Tones below the audible threshold are known as infrasonic sounds, which provoke unsettling responses in humans owing to an evolutionary associated response to natural disasters. Ultrasonic sounds are those frequencies above the audible threshold. Unlike the infrasonic signals, humans cannot detect ultrasonic events (BALL, Phillip, 2011).

Pitches at the lower end of the audible spectrum can be labelled as rumbles; for example, the sound of a passing vehicle. High-frequency pitches can be described as shrill (BALL, Phillip, 2011). While tuning of musical instruments varies in different cultures, note names repeat at specific intervals. If the frequency values of two tones have a 1:2 ratio (or any equivalent increment), they are perceived as distinguishably related pitches [5], also called an octave. Sound is perceived on a logarithmic, not linear, scale. Each octave begins at a frequency that corresponds to half the subsequent higher one, which leads to the repetitive or circulatory musical notation (LEVITIN, Daniel J, 2007). Because the mind cannot perceive a gradual linear increase in frequency, the listener experiences the shift abruptly and recognises an interval based on preconditioned expectations. For musicians, these intervals are established around musical notes. Some individuals identify the periods at exact notes and are said to have absolute pitch as they demonstrate an augmentation in the brain region associated with speech (BALL, Phillip, 2011).

The connection between pitch and the size of the speech-processing region is significant for perception. Citizens of cultures that have tonal languages (i.e., various verbal pitch cues), show similar augmentation in language processing regions (BALL, Phillip, 2011). In speech, pitch is used as a prosodic cue. Each community has its own inherent music and speech tonal grammar. For example, in the English language, a sentence ending with a high pitch syllable changes a statement into a question. In addition to learned tonal grammar, some pitches of natural events have enabled the evolution of the startle reflex. Whether learned or evolutionary, pitch associations invoke physiological and emotional responses; musicians and sound artists use these responses to convey subliminal narratives (LEVITIN, Daniel J, 2007).

Rhythm

Certain purposeful violations of the beat are often exceptionally beautiful
— C. P. E. Bach

Acoustic regularity is a common component not only in a musical arrangement, but also in ambient sound. Rhythm is a subsidiary aspect of tonal duration and a designation for the pattern and duration of a sequence of notes (LEVITIN, Daniel J, 2013). The colloquial music expression ‘beat’ is recognised when one pulse is discernible among other rhythmic pulsations and loudness serves to create emphasis. Even if there is no emphasising technique, the mind invariably attempts to structure periodic signals into a rhythm and tries to anticipate the composition. This rhythm-imposing phenomenon seems intrinsic; even infants detect a rhythm where none exists.

A series of images from an experiment exploring neurobiology of rhythm and beat perception. [Top] Schematic depictions of the auditory stimuli used in experiments [Left to Right] Auditory Waveform | Standard Musical Notation | Means rate of observed beats. [Bottom] Statistical parametric mapping (SPM) analyses. The beat versus non-beat contrasts overlaid on a template brain The experiment was conducted on two groups: Musicians and Non-Musicians subjects. Both experiments show significant bilateral activity in the Putamen (part of the Basal Ganglia) for this contrast. The main function of the putamen is to regulate movements and influence speech learn-ability. Image Reference: (GRAHN, Jessica A and Rowe, James B, 2009)

The ability to identify a repetitious pulse preconditions the mind to comprehend rhythm. Individuals from different cultures group pulses differently based on their respective languages and speech intonations (BALL, Phillip, 2011). Musicians alternate rhythms to surprise or satisfy expectations (LEVITIN, Daniel J, 2007). When the expectation is met, a sense of gratification occurs; if not met, a state of awareness or apprehension occurs. Yet, not all music has rhythm; architect and composer, Iannis Xenakis, does not use rhythm; his music is perceived as a constant tonal stream (BALL, Phillip, 2011).

Organisms such as humans or single-celled amoebas have an innate capacity to discern auditory regularity and synchronously respond to structure. Living organisms have inherent biochemical oscillators with rhythmic responses that resemble the mathematical phenomena of ‘linked oscillations’ [6] (BALL, Phillip, 2011). These biochemical oscillators are responsible for emergent behaviours such as fireflies synchronizing or strangers falling into step on a congested street (JOHNSON, Steven, 2012).

The Mapping of Mental Choreography. The brain regions contribute to dance in ways that go beyond simply carrying out motion. Diagram adapted from (BROWN, Steven and Parsons, Lawrence M, 2008)

Infants are not born with a response to rhythm and toddlers can sustain a steady rhythm sporadically. While response motor skills are not sufficiently developed during early childhood, scans show that they can discern a beat (BALL, Phillip, 2011). In adults, music with a powerful beat and tempo mediates the involvement of motor and beat perception within cerebral areas [7] (LEVITIN, Daniel J, 2013). A link is established through neural bond between the perceiving and producing rhythm regions (GRAHN, Jessica A and Rowe, James B, 2009).

Gaps in the rhythmic structure, gaps in the sort of underlying beat of the music—that sort of provides us with an opportunity to physically inhabit those gaps and fill in those gaps with our own bodies
— Neuroscientist Maria Witek ~2014

Involuntary movement (foot tap or body sway) in response to a rhythm is governed by the subcortical auditory relay station (medial geniculate nucleus) (BROWN, Steven and Parsons, Lawrence M, 2008). This synchronous motion is defined as a biological and behavioural unconscious event because of the absence of communication to cortical structures. MRI scans of subjects listening to music reveal activation in the regions of the brain that normally organise motor movements (LEVITIN, Daniel J et al., 2003). When subjects tap their feet to rhythmic patterns of various difficulties, the scans
show activation of the dorsal premotor cortex (CHEN, Joyce L et al., 2008). It is as though movement is impossible to suppress (LEVITIN, Daniel J, 2013).

Like pitch ratios, the rhythmic ratio of 2:1 appears universal. In music, the variation in rhythm urges individuals to move (dance). Doucleff (2014) reports that a rhythmic balance between predictability and complexity is favourable in music complexity. Composers use this movement-compelling phenomenon to their advantage and challenge their audiences’ expectations by shifting the emphasis of the beat, also known as syncopation. Successful music imposes syncopated patterns over an underlay of regular beats to ensure that a mental shift does not occur. This duality generates an unbalanced cognitive experience and invokes apprehension and tension (in some cases irritation). Rhythmic irregularity is not necessarily foreign to humans. Increasingly accelerated rhythms of falling and rebounding objects are habitually perceived patterns (BALL, Phillip, 2011).

Loudness

A modified loudness graph:  Auditory Experience and musical ranges charted on their corresponding locations on a Fletcher-Munson equal loudness contours for pure tones charts. Fletcher-Munson is a subjective graph created by asking hearing-human subjects to adjust the loudness as subjected to continuously increasing frequencies of pure tones. Figure adapted from (TURNER, John and Pretlove, A.J., 1991).

Loudness is a subjective psychological construct with a nonlinear relation to generated sound energy. The perceived loudness of a sound depends principally on sound pressure levels (SPL) and frequency content. The Fletcher-Munson curves shown in are the result of a large number of psychoacoustical experiments in which individuals are subjected to binaural pure tone events. The curves represent averages of the data obtained by directing a large number of subjects (regular hearing 18-25 year olds) to regulate the perceived loudness of incrementally increasing frequencies (TURNER, John and Pretlove, A.J., 1991). The reference control pressure level is 2x10-5 N/m2, which corresponds to the zero point on the loudness scale at 0 dB (INTERNATIONAL STANDARDS ORGANISATION, 1975).

The brain decodes loudness as the distance from the emitting object. The displacement distance of an oscillating object determines its perceived loudness. The rate of energy used to strike (or pluck) an object determines the rate of the resulting sound energy. Considering this definition, loudness is the mental construct of the linear physical aspect of sound energy (i.e., amplitude or maximum relative intensity). Conversely, the brain interprets amplitude into loudness logarithmically, not linearly (LEVITIN, Daniel J, 2007). 

In audiometry, the measuring unit of loudness is a phon (TURNER, John and Pretlove, A.J., 1991). In musicology and acoustics, the measuring unit is decibel (dB). These correlated units are measured on a logarithmic scale that follows the human perception of amplitude. The loudness audible range is called the dynamic range (0-140 dB), above which permanent ear damage can occur. Neurons fire at a maximum rate when an individual is subjected to sound of 115 dB. The excessive neural activity demonstrated at these levels explains the related state of sentience that concert audiences report. The slightest deviation in music loudness also communicates and triggers emotional responses (LEVITIN, Daniel J, 2007). The metaphorical techniques that musicians consider group coordination, a procedure that habitually employs loudness, pitch and rhythm variations.

Group Coordination | Spatial Location and Metaphors

A diagram illustrating the aggregation of harmonic frequencies

Through evolution, humans have acquired the survival technique to appropriate simplification, enabling the identification of edible food (vegetation and prey), disease smells (decay), and danger sounds (predator). The human brain endeavours to comprehend its surroundings holistically by developing associations between groups of stimuli. Visually, the brain groups objects by commonality in colour, form, position, continuity, or trajectory. This stimulus parsing occurs unconsciously and immediately. Similarly, the mind groups acoustical signals to map and simplify the surrounding soundscape (BALL, Phillip, 2011). Herman Von Helmholtz, the nineteenth-century acoustics pioneer, called this association process ‘unconscious inference’ (LEVITIN, Daniel J, 2007). In an attempt to balance separation and integration techniques, a continuous process of logical deductions induced from continual stimuli input (BALL, Phillip, 2011).

A diagram illustrating a harmonic wave in a string moving in the positive and negative direction.

Pure tones are seldom encountered in ambient sound, or music. Objects (or instrument) emit a collection of frequencies (pitches) corresponding to its natural oscillation frequency, also known as fundamental frequency. Fundamental frequency is a direct result of the shape, materiality and size of an object. The brain groups each set of frequencies cognitively as one acoustical entity associated with a mental image, known as timber. For example, while a quartet ensemble plays the same note, the brain classifies the sound of the violin, in contrast to the cello, as a separate unified sound (LEVITIN, Daniel J, 2007).

Pitch is a notable fundamental grouping factor that musicians use during solo performances by deviating in pitch or time slightly from the background ensemble. With this shift, the audience perceives the notes of the solo instrument as a group that is separate from the accompanying instruments. Pitch proximity grouping (i.e., related frequencies) is recognised as a melodic structure, and is significant in the soundscape of ambient sounds. Specifically, if a single sound is temporarily obscured, the brain does not interpret the emitting pitch as individual signal bursts separated by silence or other sounds. Rather, the sound is perceived as a continuous tone that increases and decreases in loudness (BALL, Phillip, 2011).

The planum temporale is a region of the brain that governs spatial mapping and handles pitch intervals and melody. This region provides a cerebral link between spatial perception and pitch, rhythm, loudness and their grouping associations (BALL, Phillip, 2011). Spatial location is another grouping principle that results from the ability to detect sound binaurally. Binaural perception uses proximity cues to regulate sound groupings. If one ear receives more than one signal at relatively the same time, the signalling objects are perceived in unity and their positions are mentally mapped as such. Humans are more sensitive to changes in position along the horizontal plane than the vertical one because the brain is less sensitive to distance moderation, but it is fine-tuned to time discrepancies as
the latter is interpreted as relative distances (LEVITIN, Daniel J, 2007).

Loudness is also a spatial cue. If all other parameters are constant, louder sounds are mapped as closer events. If the received sounds are apprehended by one ear and all equal in loudness except for one, the loudest sound is apprehended as the closest. Musicians employ all of these grouping coordinations to design audible narratives or programmable music (BALL, Phillip, 2011).

Auditory Illusion and Programmable Music

In the absence of structure, the brain strives to assert the necessary grouping procedures(BALL, Phillip, 2011). Neurologically, top-down and bottom-up processes continuously inform each other to comprehend collected signals. The constructed inferences can build an inaccurate conclusion owing to partial or indistinct stimuli input. In this case, an emerging illusion holds the mind in a cerebral loop, even if the principle is comprehended (LEVITIN, Daniel J, 2007). Musicians use these illusions to derive their compositions. For example, the structuring and speed of the consecutive notes in Sindings’ ‘Rustle of the Spring’ creates an illusory melody [8]. In Vivaldi’s ‘Four Seasons-Spring’ concerto, the intermitted high-pitch notes mimic ambient sounds to create a specific narrative (VAN CAMPEN, Cretien, 2007). The ability to comprehend these structural techniques and produce emotion is based on learned and inherited experiences as well as the neural structures of the brain (LEVITIN, Daniel J, 2007).

Through the process of ‘unconscious inference,’ a sequence of mental events creates a cerebral image. For example, the piano is physically unable to project the lowest note on the keyboard. The audience hears the note through a mental event known as the ‘filling-in’ phenomenon or ‘virtual pitch’ (MCRAINEY, Megan, 2009). Similarly, the brain perceives fragmented ambient sound as a continuous signal. This cognitive continuation is a mental process that consults other senses to complete the acquired facts, such as tactile or visual stimuli. The volume of the surrounding space is mentally mapped through a spectrum of aural cues, such as reverberations and echoes. The average person cannot specify the dimensional and material properties of a room, but he or she can successfully navigate and interact in it through acoustic cues. Recording engineers use this phenomenon to create ‘hyper-realities’ in music to mimic virtual sensory experiences because artificial reverberation actively changes the perceived proximity and location of the sound source (LEVITIN, Daniel J, 2007).

The psychological sound terminology outlined here is used customarily in more sciences (e.g., musicology and audiometry) that study human sound perception, a highly subjective feild. It is imperative to understand how sound affects users in architectural spaces. The presented facts of neurological pitch mapping and the associated low-level processes controlled by the cerebellum cement the fundamental paradigm used in this research blog. The brain uses a series of associations and grouping coordinations to comprehend and map the physical surroundings by interpreting the accompanying soundscape, thus, aural design should not be a subsidiary design method.

[1] “Music is organised sound.” – Phillip Ball (2011)

[2] The terms note and tone refer to the same abstract entity. Tone is what is heard. Note is the written symbol for tone (LEVITIN, Daniel J, 2007).

[3] Successive tones create a melody, and simultaneously played tones produce a harmony (BALL, Phillip, 2011).

[4] Infrasonic sounds are associated with supernatural experiences, and musicians and cinematographers exploit this phenomenon (BALL, Phillip, 2011).

[5] In a male-female duet, although the female singer’s vocal cords have a higher fundamental frequency than those of the male singer, they sound similar when they sing in unison (BALL, Phillip, 2011).

[6] Two oscillating pendulums attached to the same rod will eventually synchronise.

[7] The areas are: the premotor cortex, inferior frontal gyrus, superior temporal gyrus, and inferior parietal lobe (LEVITIN, Daniel J, 2013).

[8] Rustle of Spring by Christian Sinding & Chopin impromptu no. 4 in c sharp minor op. 66. The notes go so quickly that an illusory melody emerges.

Biology of Auditory Perception

Anatomy and Neurology

The brain is divided into four hemispheres, the frontal, parietal, occipital, and temporal lobes. The frontal lobe manages planning, organises perception, and governs spatial apprehension. The parietal lobe is involved in sensation and perception of various signals from the skin, ears and eyes. The occipital lobe specialises in ocular processing and spatial apprehension in conjunction with the frontal lobe. The oldest part of the brain is the cerebellum, which governs primal instincts, and is located below the temporal lobe, close to the brain stem. The cerebellum controls the motor and coordination functions, as well as emotional responses (BALL, Phillip, 2011). The primary auditory cortex resides in the temporal lobe where sound stimuli and speech semantics are first received from the ear. The temporal lobe also houses the hippocampus (long-term memory) and the amygdala (the emotional centre).

 The Anatomy of the Brain - Major sound and music computational centres of the brain. [Right] Side View: front brain is to the left [Left] Cross Section: Same orientation The Primary Auditory cortex is the first area to receive and decode pitch. It is Tonotopically Mapped. The Cerebellum is the oldest part of the brain. It is responsible for the primal response to sound (Startle and Movement). Diagram adapted from original illustrations by Mark Tramo 2001 (LEVITIN, Daniel J, 2007) and (BALL, Phillip, 2011).

The Anatomy of the Brain - Major sound and music computational centres of the brain. [Right] Side View: front brain is to the left [Left] Cross Section: Same orientation The Primary Auditory cortex is the first area to receive and decode pitch. It is Tonotopically Mapped. The Cerebellum is the oldest part of the brain. It is responsible for the primal response to sound (Startle and Movement). Diagram adapted from original illustrations by Mark Tramo 2001 (LEVITIN, Daniel J, 2007) and (BALL, Phillip, 2011).

Sound is apprehended as air vibrations. When an object is manipulated (i.e., struck or driven by an oscillating electromagnetic field), it vibrates at its fundamental frequency. A shift in state occurs, which induces oscillations (successive compressions and depressions) in the immediate encircling air. Particle vibrations propagate from the object to the outer ear (BALL, Phillip, 2011). The funnel-like form of the outer ear deflects the waves through the ear canal toward the eardrum.

 Simplified longitudinal anatomical cross section of the human ear. The ear transforms air vibrations to electro chemical brain signals through a series of mechanical and hydrodynamic systems The diagram is an adaptation of Swiss National Sound Archives’ original (FONOTECA NAZIONALE SVIZZERA).

Simplified longitudinal anatomical cross section of the human ear. The ear transforms air vibrations to electro chemical brain signals through a series of mechanical and hydrodynamic systems The diagram is an adaptation of Swiss National Sound Archives’ original (FONOTECA NAZIONALE SVIZZERA).

The small Eustachian tube connects the middle ear and mouth and equalises the atmospheric pressure on both sides of the eardrum. This equilibrium creates a state in which the membrane fluctuates only in response to minute changes in pressure caused by sound waves. The eardrum is connected to the oval window by a system of small bones in the middle ear (the malleus, incus and stapes, collectively known as the ossicles). The oval window separates the air-filled middle ear from the liquid-filled inner ear. The ossicles act as a mechanical lever system that amplifies eardrum deflections and passes the motion onto the oval window. The deflection of the oval window transforms the mechanical vibrations to the hydromechanical system of the inner ear (TURNER, John and Pretlove, A.J., 1991).

Aside from governing balance, the inner ear conducts an electrochemical process that translates acoustic vibrations into nerve signals and transmits them to the primary auditory cortex. The cochlea, a small spiral liquid-filled chamber lined with the basilar membrane and overlaid with sound-sensitive hair cells, manages this process. In response to vibrations, the cochlea hair cells oscillate within the enclosed fluid. This oscillating motion opens pores in the cell walls to release electrically charged metal atoms. The change in electric state produces neural signals that surge through the cochlear nerve fibres to the brain. These cells are tonotopically mapped (spatial organisation based on frequency); that is, different hair cells respond to different frequencies. This corresponding configuration linearly progresses along the basilar membrane; low frequencies resonate at one end and high frequencies are apprehended toward the other end (BALL, Phillip, 2011).

 Longitudinal section of an unrolled cochlea and an accompanying graph showing the response maxima. The sensitivity of different parts of the Basilar Membrane to a number of pure tonal frequencies. The Basilar Membrane is tonotopically mapped . Diagram adapted from the original by Bruel & Kjaer Ltd (TURNER, John and Pretlove, A.J., 1991).

Longitudinal section of an unrolled cochlea and an accompanying graph showing the response maxima. The sensitivity of different parts of the Basilar Membrane to a number of pure tonal frequencies. The Basilar Membrane is tonotopically mapped . Diagram adapted from the original by Bruel & Kjaer Ltd (TURNER, John and Pretlove, A.J., 1991).

Auditory cognition occurs when an audio signal changes its mechanical nature, progresses through mechanical and hydrodynamic states, and ends as an electrochemical signal at the auditory cortex. The diaphragms, levers, and sensitivity hairs enable the ear to cope with a frequency range of 20Hz to 16-20Hz (TURNER, John and Pretlove, A.J., 1991). Perception of sound depends on the decoding processes of the brain. To interpret the pitch of a sound instantly, each pitch-selective neuron in the primary auditory cortex directly connected to and dedicated exclusively for a segment of the basilar membrane to interpret the pitch of a sound instantly. This unique perceptual stimulus one-to-one neural mapping has no equivalent in any other sense.

Part of preliminary pitch and speech processing occurs in the brain stem as raw data. Electrochemical signals travel from the cochlea to the primary auditory cortex via the brain stem and the primitive, subcortical brain is triggered immediately with stimulus detection. The cerebellum decodes the rhythm, and the thalamus assesses the signal, ready to trigger a subconscious survival reflex. The thalamus then signals the amygdala to generate an emotional response (BALL, Phillip, 2011). This low-level decoding occurs before any complex cognitive processes as a primary startle response of alertness.

Once the primal evaluation is complete, all high-level processes commence and continuously register neural projections from sensory receptors and low-level processing regions. This process is termed bottom-up processing in which properties of the collected signal are separable and can change independently. Different neural circuits manage the information carried by the stimulus. Through a top-down process, high-level centres update the input data steadily, read only the overall cognitive information, and influence low-level modules. This two-way exchange integrates these signal attributes into a perceptual whole (LEVITIN, Daniel J, 2007).

The prefrontal cortex manages high-level processes such as awareness and expectations, which are the result of associations that the hippocampus creates by correlating the received signal to retained memories. The language centre (Broca) of the prefrontal cortex evaluates syntactic aspects of sound (e.g., speech or music) by transcribing pitch into language. The principal attribute in aural cognition is pitch analysis. Pitch concatenations encode an entire spectrum of sound dimensions, and the brain commissions separate modules to execute each dimension. Pitch dissection leads to melody processing, harmonic structuring, and distinct voice and timber identification. Pitch and rhythm are also the general audible characteristics required to decipher speech and ambient sound. Rhythm and event duration provide clues for pitch qualities and trigger motor responses (BALL, Phillip, 2011). This motor response explains the motivation to dance when listening to intricate rhythmic songs, and the emergent behaviour of falling into step on a crowded street (WITEK, Maria A. G. et al., 2014).

Aural Senses

The human visual and auditory senses evolved together. Unlike ears, eyes have lids, and, even in vacuum, a person can apprehend his or her heartbeat, movement of internal organs and blood flow. An example of this perception is unborn children who are aware of their surroundings through sound perception (GAUNDERLACH, Jonathan, 2007).

The auditory sense evolved primarily to increase awareness of one’s surroundings, to detect danger, and to communicate. This research recognises that spatial awareness occurs when the auditory organ receives and neural synapses decipher stimuli. Thus, the auditory sense is the primary channel of comprehension and communication. This premise is based on research and testaments of aurally impaired individuals who report that being deaf is potentially a more serious challenge than is being visually impaired. Children who are born deaf or who lose their hearing ability before language acquisition are at a greater disadvantage than are post-lingually aural disabled individuals because infants acquire a database of connections that link optical with aural memories. These associations promote the development of survival responses to signals, language acquisition and eventually logical thought. If hearing is absent at childbirth, the hearing community and surrounding environment is incompatible with the child’s communicative abilities* (SACKS, Oliver, 1989, 1990).

 Notable persons within the Deaf Community and History [Left] Alexander Melville Bell (Father) invented an alphabet for deaf people, called Visible Speech. [Right] Alexander Graham Bell (Son) invented the telephone, among other things. Original images from the Library of Congress. Image Reference: (INNOVATIONNEWSDAILY, 2012)

Notable persons within the Deaf Community and History [Left] Alexander Melville Bell (Father) invented an alphabet for deaf people, called Visible Speech. [Right] Alexander Graham Bell (Son) invented the telephone, among other things. Original images from the Library of Congress. Image Reference: (INNOVATIONNEWSDAILY, 2012)

 Ludwig van Beethoven A notable musician that lost the hearing ability during his composing years. Portrait by Joseph Karl Stieler, 1820 (3TRIOR, 2013)

Ludwig van Beethoven A notable musician that lost the hearing ability during his composing years. Portrait by Joseph Karl Stieler, 1820 (3TRIOR, 2013)

For the average hearing individual, sound defines the surrounding environment. The sonic character of one’s habitat is a compilation of sounds from a variety of sources. Humans adapt to the acoustics of their natural ecosystems (soundscapes) and the significant differences between aural and olfactory horizons. For example, where dense vegetation exists, the olfactory horizons are significantly closer than are the aural horizons. The Mayan civilization shows evidence of aural manipulations in the architecture of their temples, communities and traditions (ANITEI, Stefan, 2007).

Modern humans have readjusted to urban soundscapes, public gathering spaces and enclosed dwellings. They have accumulated a visual-aural associated memory for generations. Among the oldest sounds that have mediated the human species’ acoustic perception are geographic sonic textures such as windshield factor, adjacent bodies of water, vegetation, topography and the sounds of other species. Culture, language and communal interactions outline the overall regional pitch (BLESSER, Barry and Salter, Linda-Ruth, 2006). Post-industrial revolution technology creates noise, a polluting agent (1893). Recent research puts it more accurately: Technology creates a background of ambient sounds (SCHAFER, R. Murray, 1993). Some artists dub this phenomenon as the natural rhythm of the city (FONTANA, Bill, 2011).

There is an argument for experimental design based on individuals’ abilities to comprehend their surroundings through auditory spatial awareness. This process is a neurological conscious and unconscious reaction to spatial acoustics. When the receiver (i.e., listener) is subjected to a sonic event, physical sound waves are transformed into neural signals, sound is detected, and a cognitive process transforms the raw sensation into awareness. A visceral response is also triggered in which an elevated state of mental and physical awareness occurs (BLESSER, Barry and Salter, Linda-Ruth, 2006). 

*In Seeing Voices, Oliver Sacks explains that pre-lingually impaired individuals can still learn language and rational thought if they adopt a language compatible to their abilities, namely sign language. He explains that if a community (e.g., Martha’s Vineyard, MA) adopts sign language, aurally impaired individuals will live normally within that community (SACKS, Oliver, 1989, 1990).

Human Senses and Spatial Design

Spatial sensory qualities are typically by-products of visual configurations that address a fraction of inherited human sensations (BLESSER, Barry and Salter, Linda-Ruth, 2006). Considering these qualities, architects ordinarily design what is visually discernible. Historically, architects have designed large spaces to represent a narrative of ‘grandeur.’ For example, houses of worship and baroque castles were commonly built as large structures with immense spanning columns and high ceilings as design elements to impose a sense of reverential fear and self-abasement among individual users. This study does not declare that all historical architecture (or modern-day design) neglects to address additional human senses in their design processes. Evidence attests that the ocular sense manipulation has regularly been the primary design determinant.

Perception is never unmediated.
— Walter A. Davis (1978, p.89)

Davis’ statement affirms that the physical environment cannot exclusively be perceived visually, or only through any one sense, but rather is perceived collectively. In On the Soul, Aristotle defines that the state of being sentient is the sense by which animals perceive that they perceive. Classical Greek philosophers, like their Roman, medieval Arabic, Hebrew, and Latin counterparts denominate perception as “the common sense” (HELLER-ROAZEN, Daniel, 2007). Architectural design asserts its success when it incorporates one (or more) perceptual manipulation to communicate a singular aesthetic mental message.

Newborns possess a link between their five senses, an association comparable to the adult bond between the palate and olfactory senses. An abundance of neural bonds between the associated sensory cortices creates a perceptual unification in infants. Six months after birth, neural connections begin a purging process in response to the child’s surroundings and detach auxiliary connections.

The development of neural networks includes several anomalies. Brain scans reveal that the optic cortex in visually challenged children is active during Braille reading, a fundamentally haptic stimulus (VAN CAMPEN, Cretien, 2007). Turrell (2002), an artist, mathematician, and psychologist, bases his designs on synaesthesia, which is a neural anomaly that links the visual with other cortices. Much like the olfactory-palate neural connection, the neural pathways of synesthetic adults do not disengage fully. For example, a taste stimulus can trigger an additional visual sensation. Turrell explains that some synesthetic individuals observe colour when subjected to a sonic stimulus. Hence, the sensation produced in one modality is triggered when another is stimulated (TURRELL, James, 2002).

Programmable music is a phenomenon similar to synaesthesia and one in which average adult
experiences as an associated thought. The brain continually generates correlating visual images to comprehend aural stimuli. For instance, in Vivaldi’s Concerto (No. 1 in E major “La primavera” Spring—Four Seasons), listeners associate the intermittent high pitch notes with a bird’s song (VAN CAMPEN, Cretien, 2007). This type of associated thought also occurs in non-musical sonic contexts. Urban citizens recognise particular rhythms and frequencies with vehicular transportation and high-pitched sounds with alarms and sirens, which may signify destination or danger. Alternatively, when city inhabitants relocate to an aurally foreign environment (e.g., forest or jungle), most unseen aural events become signals for vigilance. In an unknown aural condition, the instinctual alert response occurs because the mind has not acquired the association database to discern the signals affiliated with their appropriate responses.

This study considers the programmable musical event as one circumscribing design parameter. Associated thought is linked to the programmatic use of space in the experimental and design, which can be regarded as spatial cues similar to visual components associated with spatial use. The next section discusses the physiological detection, decoding and response to different perceptual sound qualities including pitch, rhythm and loudness. These concepts constitute the paradigm of this study, the framework of the built reciprocity between urban and aural design, and the support for the proposed computational model.

Multiple Sensory Manipulation in Design

The section briefly discusses three well-known projects actively designed to manipulate more than one sense. The indicated three precedents are Yad Vesham-The Holocaust Martyrs’ and Heroes’ Remembrance Authority in Jerusalem, The Holocaust Memorial in Berlin, and The Vietnam Memorial in Washington DC. Also included here is a brief reference to James Turell’s work, which must be noted when speaking of architecture that manipulates multiple senses. The section concludes with the adoption of aural design as a subsidiary design aspect. Within the three cases, visitors’ senses are triggered in a seemingly quasi-order, setting a communicative medium for a single narrative. Every design decision aims to alter one’s perception of light, sense of equilibrium and human scale
reference. These architectural precedents use comparable design techniques, although are very different in materiality.

A single file movement, forced by tight spaces, is used in two different ways in Yad Vesham and the Berlin Holocaust Memorial (SAEHRENDT, Christian, 2005). In Yad Vesham, the main circulation artery is designed as a prism; the inscribed diameter narrows at its darkest point. In the children’s museum, the user enters through a small door that leads through bunker-like tunnels and ends in a dark room. The use of tight spaces subconsciously communicates solitude. The visual obstruction caused by those walking ahead provides a sense of trepidation of the unknown destination and a feeling of unsteadiness. The prism-like Yad Vesham walls continuously change inclination as the floor level intermittently deviates, ramping 5 degrees downward and upward. These constant planar shifts distort the visitor’s perspective (GOLDMAN, Natasha, 2006). Achieving a similar effect, the concrete blocks in the Holocaust Memorial in Berlin are the same length (238 cm) and are spaced at equal intervals of 95 cm. Like Yad Vesham, Eisenman deviates the vertical alignment of the blocks as a destabilisation design element (SAEHRENDT, Christian, 2005).

 Yad Vesham | The Holocaust Martyrs’ and Heroes’ Remembrance Authority in Jerusalem. Designed by Moshe Safdie. Image of the main circulation atrium (Mémorial de Yad Vashem).

Yad Vesham | The Holocaust Martyrs’ and Heroes’ Remembrance Authority in Jerusalem. Designed by Moshe Safdie. Image of the main circulation atrium (Mémorial de Yad Vashem).

 Memorial to the Murdered Jews of Europe - Berlin, Germany. Designed by Peter Eisenman Images curtsy of (EL RINCONCITO, 2011)

Memorial to the Murdered Jews of Europe - Berlin, Germany. Designed by Peter Eisenman Images curtsy of (EL RINCONCITO, 2011)

The children’s museum in the Yad Vesham is designed as an architectural complex of dark rooms, and mirrors line all of the walls, endlessly reflecting five candles [Refer to: Figure 2. 3] (GOLDMAN, Natasha, 2006). These features resemble the highly polished surface at the Vietnam Memorial Wall in Washington, DC. In both cases, the surfaces do not allow passive reflections, which compel the viewer to reach and touch them. Touching the Vietnam Memorial Wall verifies, solidifies, and grounds the engraved names from their apparent floating state (STURKEN, Marita, 1991). Haptic manipulation is also apparent in the Holocaust Memorial where the undulating and buckling ground forces a jerky unsteady walk (SAEHRENDT, Christian, 2005)

 Yad Vesham - Children’s museum the Holocaust Martyrs’ and Heroes’ Remembrance Authority in Jerusalem. Designed by Moshe Safdie. Image of Main Circulation Atrium by Rebecca Rosen Image Reference: (ROSEN, Rebecca, 2013).

Yad Vesham - Children’s museum the Holocaust Martyrs’ and Heroes’ Remembrance Authority in Jerusalem. Designed by Moshe Safdie. Image of Main Circulation Atrium by Rebecca Rosen Image Reference: (ROSEN, Rebecca, 2013).

It is a volcanic crater located in an area of exposed geology, the Painted Desert, an area where you feel geologic time. You have a strong feeling of standing on the surface of the planet.
— James Turrell

In the Roden Crater, Turrell manipulates the viewer’s perception of space through light (ENVIRONMENTAL GRAFFITI, n.d.). While standing in the crater and looking up, one perceives the movement of the earth. In his Wolfsburg project, Turrell succeeds in designing a space with visual illusions as the lighting is designed to eliminate all shadows. This lack of shadow contrast creates and illusion that the space has no depth (TURRELL, James, 2002).

 Vietnam Veterans Memorial - Washington DC, USA Designed by I.M. Pei in 1982 Image Reference: (COLD WAR AIR MUSEUM, 2010).

Vietnam Veterans Memorial - Washington DC, USA Designed by I.M. Pei in 1982 Image Reference: (COLD WAR AIR MUSEUM, 2010).

 James Turell Works: The Wolfsburg project at the Kunstmuseum, Germany. Exhibition between October 24th, 2009 to April 5th, 2010 Image Reference: (DESIGN BOOM, 2009 )

James Turell Works: The Wolfsburg project at the Kunstmuseum, Germany. Exhibition between October 24th, 2009 to April 5th, 2010 Image Reference: (DESIGN BOOM, 2009 )

 James Turell Works [Left] Roden Crater San Francisco Volcanic near Flagstaff, Arizona, USA. Began in 1972 unfinished work of art under construction Image curtsy of (FLATSURFACE)

James Turell Works [Left] Roden Crater San Francisco Volcanic near Flagstaff, Arizona, USA. Began in 1972 unfinished work of art under construction Image curtsy of (FLATSURFACE)

Aural Design as a Subsidiary Sense

Separately, the mentioned sense manipulations are significant design elements. Coupling sense manipulations with that of the auditory organ amplifies the narrative. What is heard, or unheard, highlights the intended subliminal narrative. The most obvious examples are found at the Memorial in Berlin and the children’s museum. Eisenman and Safdi purposefully restrict or saturate users’ visual senses, forcing them to rely on aural signals to predict what is around the next corner (GOLDMAN, Natasha, 2006). Smooth sound-reflecting surfaces lining the tight spaces reflect visitors’ low-frequency sounds (footsteps, breath and voice) back into their ears. The landscape of concrete blocks in the Holocaust Memorial and in the Vietnam Memorial Wall act as sound barriers, impeding the offsite high-frequency urban sounds from reaching visitors. The submersion of both sites places users in a position where the direct, unimpeded sound waves continue to travel above ear level. As such, visitors can see an occasional bus drive by, but they are unable to hear it. 

Many architectural precedents are designed for more than one sense to act as the primary sense during the experience. The reoccurring pattern in these projects is their exclusive use (i.e., memorials and museums dedicated to human trauma). Architects are aware that humans use all of their senses when experiencing their surroundings. Designers who attempt to convey a particular emotional narrative use false visual cues, planar and horizon shifts, and blocking of specific senses as design elements to achieve the desired experience.

The hypothesis aims to use the mentioned design methods regularly; not in particular design cases. Researchers argue that architects design visual architectural elements primarily because vision is the primary and hearing is the secondary sense. The next section establishes that this argument inaccurate. In actuality, the aural sense is connected uniquely to more than one cognitive process as humans instinctively respond to sound and map their environments mentally through separate conscious and subconscious processes.