Linkage and Displacement: Moving Sound

Despite the sophisticated process through which we localize sounds, I am wondering if there is a way to “trick” someone into perceiving a source apart from its original location.  Obviously there are some difficulties in achieving this kind of effect, namely as a sound travels from its source, its power diminishes by the square of the distance traveled.  Also, as it encounters successive surfaces, every reflection “colors” sound and effectively alters it.  Additionally, high frequencies are more quickly damped by air than low frequencies, thereby filtering them out and leaving the more muffled low frequencies to travel the farthest distances.  

Regardless, there are still ways to "transport" sound across relatively large distances by architectural means.  Whispering galleries are one example of this phenomenon.  In St. Paul's Cathedral dome in London, or at the Echo Wall at the Temple of Heaven in Beijing (among others) two people can stand hundreds of feet apart (at opposite sides of the curve) and carry out a conversation in a normal speaking voice.  

Alternatively, parabolic mirrors are able to focus, but also reflect sound in such a way that it can be received and focused by another parabolic dish located a distance way.  I have done a little experiment below in Falstad Ripple that shows one way to employ partial ellipses and/or parabolic reflectors.  Let us say that the source is located within the elliptical section that is furthest to the left.  The receiver/listener is located in the middle elliptical section with its back to the source.   In this way the listener cannot see the source.  Through the positioning of another elliptical section that collects and then reflects the original signal, the listener will perceive the source, however, understander the source as being the right most elliptical section.  This example is one way that nested volumes might be able to displace sound, thereby affecting the perception of our sonic surroundings. 

 

 

I think it is also important to think about sound transmission between adjacent sound environments and the possibility of acoustically linking spaces that perhaps are physically separate.  In addition to structure-borne sounds (vibrations that travel through solid building elements such as columns, beams and floors slabs) which may subsequently be radiated as airborne sound great distances away from the source, I am interested in intentionally using methods to create a network of sound spaces that exists in direct relation to the environment one is occupying.

In this discussion I am interested less in the actual qualities of each space and more in the relationships between spaces.  The diagrams below start to illustrate possible connections between vertical spaces.  Can the sound of one floor be acoustically joined with another while bypassing others?  Is this done by physically piercing through one floor to get to the other?

 

 

 

Whether we are aware of it or not, we are constantly processing numerous layers of aural information as we move through spaces over time.  The sounds of the outdoor environment may be significantly lessened when we occupy interior spaces, but they are by no means completely shut out.  I propose that we begin to consciously engage and manipulate these layers of aural information through architectural constructs and interventions as a way to shape experience.

Architectural Elements as Acoustic Filters

In addition to walls enclosing, dividing, and delineating space, I would like to explore the possible manipulation of their ability to alter aural perception from one side to the other.  While it is an inherent property of a wall to block and filter, to some extent, the sound environment that exists opposite the side of one's occupation, it is also an opportunity to reinterpret the spaces that we inhabit.  The following ideas are initial thoughts on how the structure of a wall can be appropriated in order to influence alternative aural experiences.

Cones:

One possible construct is that of cones penetrating a wall.  On one side you are presented with the bells of the cones that are flush with the wall.  On the other, you encounter the three-dimensional surface of the cone tips projecting through the wall and out into the space.  The intent is to create two opposed spatial and aural experiences.  In addition to the effect of filtering the natural sound environment from one side to the other, the interactive aspect of the construct could also invite alternative modes of activation.  Cones could be used for broadcasting messages from one side to the other, or for discrete eavesdropping.  Any number of variations could be explored in order to develop an approach that effectively alters the acoustic quality of the spaces adjacent to the wall, whether interior or exterior.  Perhaps their geometries are not as regular as the array presented below, or the scales of the cones are more diverse.  Also, because of the directional quality of the cones, their angles of projection could be varied in order to distribute the source sounds in a more dynamic way.  The images below are just a start.

 

Precedents: La Monte Young and Michael Asher

La Monte Young
Dream House: Sound and Light Environment 
http://melafoundation.org/main.htm

Source: http://melafoundation.org/main.htm

           

            Dream House is a sound and light environment created by composer La Monte Young and artist Marian Zazeela in their TriBeCa apartment in New York City.  The installation has been running on and off for the last twenty years, and though I have yet to experience the work, from the text written about it and the short clips on YouTube that I found (posted below), Young’s intention to use sound and light to enhance attention spans and increase sensitivity to differences within a space directly relates to my interest in the effect of standing waves and room modes on occupants in relation to the built environment referred to in the previous post.

            This piece is situated within several rooms of the apartment and is characterized by the magenta glow of Zazeela’s lights and Young's sound environment created from sine wave components generated digitally in real time on a custom designed Rayna interval synthesizer.  Ed Howard describes the resulting phenomenon in his 2003 article in Stylus Magazine:

“In each corner is a tall white speaker that looks like a giant refrigerator, as intimidating in the bare space as Stanley Kubrick’s monolith.  These monoliths are vibrating with the 32 frequencies of Young’s composition, and though the music itself stays constant no matter how long is spent inside the House, the sound’s relationship to its listeners can change drastically with the slightest movements.

The only time the music remains stable is when the listener is completely still: the low drones culminate in a dense jackhammer cloud as they cross over each other, forming complex rhythms.  However, just slight changes in posture completely alter the sound field.  Different higher pitches appear as you move your head; by rocking slowly back and forth, you can create a hypnotic two-note melody as the high tones shift and spin dizzyingly.  Towards the center of the main room, the drones are thickest and lowest, while around the perimeter of the room the sound tends to be airier, dominated by chattery high-end whine.”

I am intrigued by this work as a physically executed full scale installation that exists within a complex set of spaces and which succeeds in focusing one’s attention on the effects that every subtle movement can have on our aural perception of the built environment.  I would like to further explore in the direction of revealing the inherent acoustic properties of a space while locating them within a surrounding contextual soundscape.

VIDEO: 

standing in Dream House, NYC

moving in Dream House, NYC


Michael Asher 
February 13 - March 8, 1970
Gladys K. Montgomery Art Center at Pomona College
Claremont, CA 

Source: http://www.pomona.edu/museum/exhibitions/pstpomona/

Michael Asher’s project at Pomona College in 1970 was successful in creating a physical and acoustic experience without the use of sound generating equipment, simply by shaping the space one occupies in the environment.  The installation consisted of three walls constructed of drywall on wood framing that delineated two triangular areas, one larger located in the gallery and one smaller situated in the lobby.  Additionally, a ceiling was constructed at a height of 6’10” throughout the entire space.  The resulting corridor between the two spaces, only two feet wide, created an experience of compression and expansion in both movement and in sound. 

            A unique characteristic of this installation is that it was open to the public 24 hours a day.  The existing lobby doors were removed and their frame was covered by the new wall construction.  Subsequently, exterior light, sound and air became a permanent part of the exhibition, effectively shaping the very experience one had within the space.  The sound in the piece consisted of the activity of the community surrounding the work as well as that of viewers who entered it.  In this way, the installation captured and reframed the greater public sphere within the controlled physical environment of the constructed space where it could then be interpreted by the viewer.

Source: Writings 1973-1983 on Works 1969-1979, Michael Asher (pg 35)

The image below is a simulation that I was experimenting with which attempts to show the hypothetical behavior of sound waves within the space.  Using the Falstad Ripple applet I was able to sketch out a diagrammatic plan of the installation and by placing a source outside of “the doors”, demonstrate how the signal may travel and interact with the physical boundaries of the space.  What can be seen from these diagrams is the way in which the first angled wall reflects and directs the sound through the corridor and then into the larger triangular area of the gallery, collecting at the back wall, where, according to those that experienced the installation, the environmental sounds were perceived to be the loudest. 

Falstad Ripple simulation

Michael Asher
December 30, 1969 - March 1, 1970
Spaces
Museum of Modern Art
New York, New York

Source: Writings 1973-1983 on Works 1969-1979, Michael Asher (pg 29)

While researching Michael Asher’s installation for the Spaces exhibit at MOMA I was particularly interested in the method of construction in order to achieve a specific acoustic effect.  Due to the location of the given space within the context of a larger exhibit, it was necessary for Asher to construct new walls and alter existing walls in order to isolate the room acoustically from the surrounding spaces.  In addition to filling the existing walls with fiberglass insulating material, Asher added two layers of wall to all interior surfaces.  These two additional wall layers were separated by a 1” air space which served as an acoustical plenum (there is a high impedance mismatch between sound moving through the structure and through the air).  Also, each section stood on rubber pads to isolate them from vibrations affecting the building.  A wood joist ceiling was constructed six feet below the existing ceiling.  Fiberglass acoustical insulation material 2” thick was then placed above the constructed ceiling. 

Source: Writings 1973-1983 on Works 1969-1979, Michael Asher (pg 25)

The resulting space was intended to absorb sound and be acoustically isolated from the adjacent spaces, particularly the open hallway on two sides.   Asher describes the work in his book:

“The work was itself isolated from the museum, yet functioned by simultaneously interacting the sound and light produced within the museum.  Once these sounds had entered the work, they were structured on a diagonal axis and were ultimately dissolved within the confines of the installation.”

Through the use of construction materials and methods, Asher was able to create a space that separated itself from its surroundings without completely enclosing the room, eliminating sound sources or physically removing the installation to a different location.  To enter and inhabit a space of drastically different acoustic quality from its context, Asher allows us to re-frame our perception of sound environment as we move through various spaces over time.

Source: Writings 1973-1983 on Works 1969-1979, Michael Asher (pg 27)

Interference Distribution and Room Modes

“The whole room may be mapped out into regions in which the sound is loud and regions in which it is feeble.” –Collected Papers on Acoustics, Wallace Clement Sabine

Resonant frequencies occur in every enclosed space.  The frequency of each resonance is directly related to the room's dimensions.  When a sound is played having the same frequency as a natural resonance of the room, that note will sound much louder as a result of constructive interference, or weaker due to destructive interference, depending on the listener's physical position within the space.

Wallace Clement Sabine describes this phenomena in The Collected Papers on Acoustics using the image below.

This image describes the distribution of sound intensity at the head level of the Congregational Church in Naugatuck, Connecticut.  This particular space has a barrel-shaped ceiling with the center of curvature on the floor level.  It should also be noted that the sound source in this study when Sabine conducted it was placed in the center of the space.  The distribution of sound intensities are expressed using the language of a topographical landscape map. 

I am interested in deliberately exposing this specific property of enclosed spaces in order to make the occupant aware of the fundamental relationship between body position, built environment and aural experience. 

A cubic room will exhibit three resonances at the same frequency since its dimensions are all equal.  I propose that a room is constructed with the dimensions of a cube, 3m x 3m x 3m.  Built within a controlled setting (interior space?), the construction should be made of masonry or of otherwise massive and reflective material with a smooth interior surface.  The standing room modes for this volume are calculated using the room mode calculator and visualization tool found here. 

The dark regions are areas of high sound pressure and are therefore louder in intensity.  As you can see, interference alters the distribution of sound in the room "causing the intensity of any one pure sustained note to be above or below the average intensity at near points." (Collected Papers on Acoustics)  This phenomena is constant so long as the source of sound is continued. 

            Axial modes at 57Hz, 115Hz…

            Tangential modes at 81Hz, 128Hz…

            Oblique mode at 99Hz…

Within this 3m x 3m x 3m cubic room a sound signal will be placed in the center of the space and will excite the axial frequencies (since they are the most pronounced).  Later perhaps, other frequencies and/or complex signals can be employed to further study the relationship between the interference system within the given space.  

This construct will serve as an experimental environment within which the properties of a sound signal can be experienced in direct relation to an enclosed space.  As the visitor moves throughout the space he will encounter areas of uncomfortably high sound intensity and practically inaudible sound intensity which will encourage a new understanding and awareness of the space one occupies.

The natural resonant frequencies of an enclosed space can be determined using the 20Hz-200Hz swept sines found here. 

Understanding Space through Sound

How can sound be shaped by spaces and how can people’s experiences be affected through the manipulation of acoustics as a function of architecture?    

“…no sound exists outside of space, and no space is ever truly silent.  Sound and space mutually reinforce one another in our perception; the qualities of a space affect how we perceive a sound and those of a sound affect how we perceive a space.” Colin Ripley, In the Place of Sound

 “…by listening we may be able to perceive the relationship between subject and object, inside and outside, and the public and private altogether differently.”  Michael Bull and Les Black, The Auditory Cultural Reader 

SHAPE (size) and MATERIAL

            I would like to investigate the shaping of experience through the acoustical characteristics of architectural constructs, specifically through the use of observed properties of geometric spaces, phenomena resulting from the relationships between adjacent spaces, as well as the use of materials and placement of objects within a space to enhance or distort existing soundscapes.

            More specifically, I am interested in how these criteria might be employed in order to create aurally specific spaces.  For instance, a reverberant passageway that slowly transitions to an insulated environment simply through the use of materials and their composition.  Another example could be orchestrating the absence of sound in an extremely ambient space.  As these phenomena are a result of specific spatial configurations, their classification as such will begin to organize strategies for the development of possible aural interventions.  Topics for study would include: the acoustics of interior and exterior spaces addressing the possible disjunction between the aural and the visual, soundscapes of stacked spaces, embedded spaces etc., the properties of space geometries, and the characteristics of materials and their construction.

Interference, Reverberation and Resonance

            Additionally, I would like to explore the physical relationship people have with the spaces they occupy with regards to acoustic perception.  One might have drastically different experiences from different positions within a room as suggested in the excerpt below from Sabine’s Collected Papers on Acoustics.

                “…it was observed that the pitch of the pipe apparently changed an octave when the observer straightened up in his chair from a position in which he was leaning forward.  The explanation is this: The organ pipe did not give a single pure note, but gave a fundamental treble c accompanied by several overtones, of which the strongest was in this case the octave above.  Each note in the whole complex sound had its own interference system, which as long as the sound remained constant, remained fixed in position.” (pg. 7)

            It is evident that spaces possess certain inherent acoustic qualities, including those of interference (related to a produced signal), reverberation and resonance, but the experience of a signal can also depend on the position of the body in relation to the physical space it occupies.  For example, when one speaks facing a wall or corner, the sound will be louder (actually more powerful), than if you speak directly at a person.

            I am interested in the possibilities presented by these types of interactions between the body and the built environment.  How can these phenomena consciously be employed to create specific acoustic and architectural experiences? Within the framework of the themes above, acoustic interventions can serve as the interface through which people begin to observe and affect their status in the greater public sphere.