Sound-as-Space

The Spatial Sound With Supercollider workshop has come to a close.  Thank you to the folks at CCRMA and GAFFTA for hosting!

Before expanding on some of the techniques that came up in the workshop, I think it would be useful to take a few steps backward and explain what it means to spatialize sound.

We can think of sound as a process which occurs in time  i.e.  I listened to Rachmaninoff's Symphony No. 2 in E Minor, Op. 27 in Allegro molto for nine minutes and 38 seconds on my ipod.  Even when listening to sound on headphones--there is a spatiality.  Sound is always resonating in a space, even if it is the tiny space between the headphones and the inner ear.

We can also think of sound as an object--a source--which produces vibrations in space i.e.  I can hear a garbage truck outside my house and up the street.  A great deal of sound spatialization is about decoding the ways that we are able to construct the location of a sound's source.

Sound will reach the ears at slightly different times.
The sound is then perceived to have a directionality.

Just as we need two eyes to perceive depth, we need two ears to locate sound.  The phase difference in a wave (meaning two waves traveling out-of-sync) when a sound hits one ear and then the other is one method our brain uses to locate a sound.  Other techniques which relate to binaural hearing depend on the particular form of our outer ear and the acoustic shadows that are cast by our head when sounds are to the left, right, or at some elevation above the horizontal plane.

So far these spatialization techniques refer to a source-listener relationship.  A sound--a pressure wave--is emitted from a source and after a period of time and a certain reduction in the signal strength it reaches our ears and is perceived to have a distance and direction from the listener.

Yet there is another, more interesting (or at least more architectural) way to think about spatializing sound, and that is to think of sound as the space between source and listener.  So rather than thinking about what emits the sound (the object) or what the sound is perceived as (by the listener), we simply think about sound as the vibration of something within a space.  That 'something' is usually air, but anything which can vibrate--that is, all matter--can transmit a sound.  There is space inside of a chunk of lead.  But I digress: the important point here is that to become aware of sound as a field condition, one must divorce oneself from the position of an observer listening to a source of sound.

There are a set of questions situated around how this spatial field is constructed and inhabited.  If we are talking about producing this space virtually, about capturing this space in some kind of digital format, how do we go about doing that?  And once it is captured, how is it reproduced?  And finally, how do we understand and navigate through a virtual space projected into a real space?

The 8-channel speaker setup at the GAFFTA workshop.
The dashed-line indicates a virtual space reconstructed by the listener.  

In the case of our workshop, we had an eight-speaker array on which we listened to some pretty awesome pieces of sound.  (Some were composed by one of the co-teachers in the workshop, Fernando Lopez-Lezcano, for even larger arrays of speakers).  I think a lot of the stuff we listened to can be called soundscapes.  These sonic landscapes were projected into our space and moved around the room via the speakers, but not necessarily constructing a geometrically-specific virtual space.

Listening in this 8-channel environment is ideal at the sweet-spot.  Located at the center of the array, this location provided the most accurate spatialization, as the speakers are calculated to project sound into this infinitely small point in space at the same time.

One thing I am curious about is how to move that sweet spot.  Let's say you have a crowd of people within the array, and you want to project, let's say, a claustrophobic space on certain individuals within the crowd.  I posed this possibility to the workshop leaders, and we decided that it is possible to move the sweet-spot around by adjusting the time delay of the speakers.  As long as the array is calibrated precisely, there could be a moving location inside of the array that could receive sound from all the sources at the same time.  Imagine running around with your ears out trying to follow this invisible point in space!

A virtual space is shuffled around inside of the speaker array.

It gets much more complicated, apparently, when you try to move this 'claustrophobic space' around along with the sweet-spot.  Apparently this would require decoding the space inside the loudspeaker.  I'm still not sure what that means, but it sounds like fun to me.  The workshop coordinators, however, didn't think it was possible.  The problem, I believe, is that we are dealing with simple trigonometry when we project a sound into a point in space (the location of the listener).  However, an architectural fragment of spatial sound, with three dimensions, is not a point in space-- it is a field condition.  And a single speaker is not capable of mapping this space--it depends upon the array of speakers to do this.

So, how can we project a spatial field into another spatial field?  Overlapping soundscrapers.  I'm working on it.

A Machine for Slicing Rooms

I am almost finished with a four-day workshop hosted by the Gray Area Foundation for the Arts (GAFFTA) in the Tenderloin district of San Francisco.  The title is "Spatial Sound with Supercollider".  In this workshop we have concerned ourselves with the manifold possibilities for taking sound and expanding it from the standard stereo listening environment.  This spatialization of sound is distinct from widely available standards such as Dolby Surround Sound in that we are digging into the components which reproduce spatial effects.  The program called Supercollider allows an incredible amount of control in how a recorded sound, even a mono-channel recording, can be reproduced for the listener with rich three-dimensionality.

In the workshop we have ooh'd and aah'd over the complexity involved in producing something like third-order ambisonics, where a sound source appears to cease emerging from the speakers and instead has a presence of its own in the room.

(red represents the  positive phase and green represents the negative phase of a sound)

In the above image, 16 different spherical dispersion models are used to reproduce a single 3-dimensional space.  The math to assemble these models and then disperse them into a multi-channel speaker array is heavy though not advanced, being entirely based upon sines and cosines.  These models for the dispersion of sound can be seen as the atomization of a space.  Each globe represents a directionality that, when combined with the other 'atoms' and decoded to a speaker array of your design, will produce a precise virtual environment.  Sound is not merely a temporal phenomenon; we are hearing space when we listen to a spatialized recording.

I find the analog versions of spatializing sound just as interesting as the digital models.  And for those sound engineers and musicians who are nostalgic for the sound that these analog reverb machines once produced, there are digital filters which simulate all the distortion and 'badness' that these setups are known for.

Plate reverb is particularly interesting because it is a two-dimensional machine that can produce the reverberation characteristics of a room, deceitfully producing a three-dimensional space.  It works simply like this: an electro-mechanical transducer produces vibration in a large metal plate which is held in tension.  A pickup (or two pickups for stereo sound) then records the new sound which has taken on the reverberation properties of the sheet of metal.  Check out this video which demonstrates some plate reverb effects.

The EMT 240 uses a 12" square gold foil sheet in tension to simulate the reverb in a room.

The plate is like an architectural slice of a room, where introduced sound produces wave-effects in the tensioned metal sheet just as it would in a real space.  Imagine then a whole building section represented inside a plate reverb machine.

Scientifically, we might be able to produce precise reverb filters of building sections, just as the physicist  Wallace Sabine did for the New Theatre, New York in 1913.  These plans and sections, modeled using the Schlieren method, describe the complex fluid dynamics of reverberant sound.

We are covering lots of fascinating techniques including HRTF (Head Related Transfer Function).  Each of these systems require the decoding of a mechanism which tells the brain where to find a sound in space.  It's a highly architectural exercise.

Off to Burn

Just about to take off on a week-long odyssey into the Nevada desert. Of course, I won't be alone. I'll be joined by about 40,000 people who gather each year and construct the temporary metropolis known as Black Rock City. I've been looking forward to my first trip to Burning Man all year but I've withheld expectations. My plan all along was just to show up, sound recorder in hand, and just absorb the place.

But last night everything changed, at my house-mate's insistence. A piece from my thesis, a 4-foot long, 10-inch diameter bass cannon powered by an Aura 50-watt bass shaker will be coming along. What am I going to do with it? I have tentative plans, should the desert accept them. I'll post about successes and failures when I get back.

Well, it has been a summer of imagining temporary things. In June, together with architect/skater Matt Baran, I developed SOUNDSKATE, a skateable infrastructure which brings the non-skating public into a playful intersection with skaters through the re-mixing of the sounds of skating (design details to be posted at a later date).

SOUNDSKATE by Nick Sowers and Matt Baran

The idea is that this set of quarter pipes and half pipes--the standard skating infrastructure-- would be augmented with resonance chambers, tubes, and surfaces which would produce interesting sound effects. Skaters would then go about creating a personal skating routine full of riffs, bridges, choruses and, of course, self-indulgent solos. The "noise" of skating is thus turned into a noise-music soundtrack. SOUNDSKATE amplifies the sound of skating and in so doing, it aspires to bring acceptance and interest in skating to a wider public.

SOUNDSKATE by Nick Sowers and Matt Baran

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For another temporary installation, I took part in the Sukkah City competition--an opportunity to re-think the sukkah, a temporary structure which is put up for seven days during the Jewish holiday of Sukkot.

Though not selected as a finalist, I am still convinced that I should realize my sukkah. The concept was pretty straightforward: build a sukkah in California, record the sounds of making it, then destroy it (record that sound as well) and re-project the sukkah in Union Square Park, NYC. I have half a mind to just bring a PA system and blast my sonic sukkah throughout the park. Alas I will be in Texas, not New York, at the beginning of Sukkot.

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I'm packing up gear for Burning Man tonight. The most precious cargo is: a ZOOM H4n recorder and a set of microphones (a pair of stereo binaurals, one omni-condenser and one omni dynamic cardioid).

There are a number of installations at Burning Man that I am looking forward to listening to. One that stands out is Sounds from the Urban Innerground which is set up at the base of the giant man. It will be playing sound from cities around the world continuously for 24 hours corresponding roughly to the time when the sounds were recorded in their respective locations. So I could be up at dawn in the desert of Nevada and listening to the sounds of Mumbai's rush hour.

There is a lot of sound art I expect to find that won't even be dubbed as 'sound art' (part of what I love about this kind of art). These will be sonic experiences, minute and perhaps even mute, evoking through the vibration of air the connection people share in a rare place like Black Rock City.

It's exciting to be a part of such a large, leave-no-trace event. It's inevitable that how you destroy or dismantle what you take with you factors into the design of what you bring. This is the power of sound: to record these constructions and deconstructions with a medium that is the essence of temporary.

See you on the flip side of the Burn.

Dispatches from the Fortress of Eden

Park Avenue, Adobe Systems Inc., via Google Streetview

It's another sunny day in downtown San Jose, just like everyday is on Google Streetview.  The fog of San Francisco never seems to get close.  It's just an average day like this that two of DEMILIT's members, myself and Bryan Finoki, decide to have a look around.

We're getting ready for an installation at the SJ01 San Jose Biennale next month.  Our group (also including Javier Arbona) is a loose one based upon a collective gravitation toward military landscapes.  Each of us will define differently what a 'military landscape' is, what our methods for exploring them are, and what sorts of projects we envision out of them.  But the fact of the matter is we're hooked on 'em, and they don't seem to be going away any time soon.

Details will follow on what DEMILIT is up to, who is coming to speak, and the installations that we are preparing for SJ01  One thing we'd like to get people involved with is a guided tour of the militarization of downtown San Jose.  So Bryan and I made an adventure out of our first practice run.

It was our first visit as pedestrians in downtown San Jose.  We had little idea what, if anything, we would find.  I anticipated large stretches of boring, smooth, generic downtown urban space.  We definitely saw some of that.  In these sorts of mundane places, however, the clues for how the urban environment is shaped by invisible sources of power are best detected.  What is it that makes us feel safe in a city?  Is this security based on anything real, or do we depend upon invisible factors and codes that buttress our corporate-consumer culture?

San Jose City Hall, Richard Meier, completed in 2005

Bryan and I spotted the City Hall and decided to linger in the large plaza.  Bollards of many typologies (flagpoles, rocks, fountains, and our favorite--poles spouting mist (wanna-be San Francisco fog?) ) buffer the plaza from Santa Clara St.  The space definitely has some military-urbanist planning codes informing the proportions, the standoff distances, etc.  I'll leave that for a future post to delve into.

We also walked the perimeter of Adobe's corporate park, and we discussed some of its features.  Lacking the glorious allusions to the elegant geometries of traditional fortresses (epaulette, ravelin, Priest's Cap, bastions with ciruclar flanks, etc), we are left with the viewing cones of surveillance cameras and blank walls of ground-floor mechanical rooms to understand its fortress nature.  Listen:

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Bryan and I then traversed the innocuous San Jose landscape to an office tower at 225 W. Santa Clara Ave.  At an elusive Suite 1600, one can find the offices of Jeppesen, a Boeing subsidiary which allegedly assisted with the trip planning of CIA rendition flights.  I'll leave it to Bryan to fill in details at another time.  For now, we just want to knock on their door.  You know, we're wondering if they are hiring.  Listen:

That's it for now.  There is a lot more work to be done in order to understand the place of San Jose in the larger Bay Area fortification.  We'll also be looking at the former blimp hangars at Moffett Field and the  Mission Santa Clara de Asís as components of this military landscape.  San Jose, from fruit orchards to pyramids of silicon, is not as obvious as the military landscapes of Alameda, Richmond, and the Presidio, but it is our task to demonstrate how it is a military landscape and through this task, we may come to learn more about our own assumptions and ways of looking at these landscapes.