Silence, aircraft noises, and harmonies in pain

“Silence, aircraft noises, and harmonies in pain” is an audio project designed to be presented in ambisonics sound system. I would like at the beginning to mention some things about the acoustic situation in venues in general, and more specifically about this project.

Listen to a sample from Silence, aircraft noises, and harmonies in pain

In the case of achieving the profound listening, which for me is the most important thing in every audio act, it is totally necessary to acoustically isolate the venue from every possible (or impossible) noisy surroundings. A central table where all of the equipment is set on. Ambisonics soundsystem sometimes works better when the audience moves because it receives different audio “icons” depending on the spot, the height and the distance from each speaker, so it would be interesting to see the people moving during the show.

It is undeniable that what the musician listens through the monitors on stage and what the audience receives are two different things. It does not has just to do with the volume. The sound engineer has the control of the final result and by EQ-ing, panning, balancing, mixing etc he is in a way “creating” the sound that the audience listens to. So, no need of front of house console for mixing, panning, balancing, but it is really essential to have a mix board after the one I use to route my audio signals as discrete in separate channels (4, each for one speaker). Also, in some musical perfomances there is no need of watching the musician. In this project the sound perception is simultaneously multi- directional, so total darkness would be really helpful.

The project consists of three parts:

At the first part, “SILENCE,” a real time recording of the very “tiny” sounds of the space (people breathing, speaking, legs moving, the ambience of the room, the impossible to isolate sounds of inside or outside) will be recorded and played back. The human ear rarely catches what some microphones are able to capture but the sound, audible or not, is always there. The recording will be played back once or twice and it will be recorded again in case to perceive the resonance of the space, the “invisible” audio situation of the room.

I wish I could use a tetra mic for that but even one (stereo X,Y) or two, good condenser microphones would do the job. The TetraMic allows somebody to place a single exceedingly accurate tetrahedral microphone in a sound field, record four channels of audio in “A” format, transform them in a computer into “B” format (W, X, Y and Z), and later decode those four channels to essentially any playback format including mono, stereo, 5.1, 7.1, 10.1 (e.g. 5.1 with height information), binaural and many others.

This process would allow this audio project to have unparalleled flexibility. Real time manipulation of the twice recorded room’s acoustic situation will be follow. The conception of a recorded sound as something with own entity by itself, independent of its source, which has only been physically possible since the technical development of electromechanical means of fixation and reproduction of sound, fits perfect with the starting part.

These sounds we hear randomly in everyday life and they can become an always present and available public domainworld of constant reproduction are highly important and responsible for many mental and health effects. We live in a world of constant reproduction where everything is being repeated by itself. This is always happening with the sound around us and here comes in the surface the importancy of recording “invisible” audio situations in empty, or full of people spaces.

The second part, “AIRCRAFT NOISES” is the main audio part of this project. Being obsessed from my childhood with airports and airplanes I started recording their sounds in 2004. But how noise and especially noise coming from aircrafts “lives” beside us? Few words about this: In industrialized countries elevated sound levels have been always been one of the most widespread public health threats. Aerodynamic noise exposure is responsible for several diseases such as like tinnitus, hypertension, vasoconstriction and other cardiovascular impacts. Ten percent of the people in industrialized societies have hearing loss, and millions are steadily progressing to that outcome.

The major source of hearing loss is the exposure to elevated sound levels. However, more careful investigations showed that cumulative exposure to relatively moderate levels, such as 70 dB can lead to the irreversible loss of hearing. Besides that, simple annoyance could be mentioned as one of the disturbing effects of aircrafts noise. Annoyance effects of noise vary greatly by demographics and by the perception of how useful the entity is that originates the noise. For example, aircraft mechanics who live near an airport are less likely to be complainants, since their livelihood is based upon airport operations. Annoyance is also influenced by whether the noise source is visible, whether it has pure tones or hammer effects and whether the recipient believes the noise can be controlled. In any case, the onset of noise complaints can be as low as 40 dB.

The threshold for sleep interference is 45 dB or lower, and the onset of speech interference is about 63 dB. After that, it’s obvious how a level of above 70 dB could affect humans. J.M. Field examines a variety of these outcomes and finds significant influence of moderate-level environmental noise upon human behaviour and mood. Stress is steadily rising and mental health (including disengagement and increases in aggressive behaviors) is always under danger. In order to work against the aircraft noise to humans, monitoring systems around and in airports have developed including aircaft noise server, noise monitoring software and aircart noise database (FAA).

So, after that why a sound project could use aircaft noises, since they are simply dangerous? One reason is that due to loud music and a generally noisy environment, young people in the United States have a rate of impaired hearing 2.5 times greater than their parents and grandparents. This will be soon counted and in other countries. This is a very important fact for me. Also, there is always the “musical” part: by flying in an aeroplane (and concentrating to the cabin’s ambience), by listening its taking off, its landing, the “squeezing” of war aircrafts, I have been always founding musical elements. This is one of the sounds that totally filled up my head. My effort is to convert and transform them into pure musical sound. The danger of the exposure in the aircarft’s noise could be determined, dissapear and be enjoyable and pleasant by listen to it in a concert space.

“HARMONIES IN PAIN” follows. This will be a typical Novi_sad audio perfomance mixed with some sounds from airplanes (ambiences, spoken words, heavy drone flights, etc). Environmental recordings will be used, digitally processed and manipulated internal in the computer and on the mix board in real time. Harmonic melodies, overtones and structured digital noise will create a transcedental atmosphere in which the audience is being called to close the eyes. Most of the stuff from the aircraft sounds has been recorded in flights through Canada, Europe, and United States. Air Canada, Lufthansa and Delta Airlines are some of the flying companies who have been gently audio hijacked from me. Also some war aircrafts landings and taking offs will be heard. These are from war airports in Greece.

Now I will try to explain why I’d like to present this project in ambisonics soundsystem. But first few words about quadraphonic, a sound system which pre-existed.

Quadraphonic has been introduced in the U.S market at the early 70’s. It uses four channels in which speakers are positioned at all four corners of the listening space, reproducing signals that are independent of each other. The rear sound level in a live performance is about 7 dB below the front, but clearly audible.

If rear speakers are fed with the difference between the stereo channels, audience noises and echoes from the auditorium can be heard from behind the listener. This can be most easily achieved by wiring two similar additional rear speakers in series between the live feeds from the stereo amplifier. But, there is always a difference in between the sound that comes from the rear and the front speakers.

Ambisonics on the other hand is a multi channel mixing technology which is isotropic in that sounds arriving from all directions are treated equally (as opposed to most other surround systems that assume that the main sources of sound are frontal and that rear channels are only for ambience or special effects).

All speakers are generally used to localise a sound in any direction. This gives better localisation, particularly to the sides and rear. The stability and imaging of the reproduced soundfield vary less with listener position than with most other surround systems. The soundfield can even be appreciated by listeners outside the speaker array. In the basic version, known as first-order Ambisonics, sound information is encoded into four channels: W, X, Y and Z. This is called Ambisonic B-format. The W channel is the general mono level of the signal, corresponding to the output of an omnidirectional microphone. The B-format is the standard audio format produced by a Soundfield kit.

It consists of the following four signals:

W – A pressure signal (mono) corresponding to the output from an omnidirectional microphone
X – The front-to-back directional information, a forward-pointing velocity or “figure-of-eight” microphone
Y – The side-to-side directional information, a leftward-pointing figure-of-eight microphone
Z – The up-to-down directional information, an upward-pointing figure-of-eight microphone.
This would be able to reproduce the “height” of the sound but hardly the depth, but Ambisonics provides significant advantages in that the effect does not sound significantly listener- or speaker-dependent (you can even walk outside the speakers and appreciate the image).

The major advantages of Ambisonics are:

-The surround-sound image remains largely unaffected by listener position (no “sweet spot”), and this is highly important for large gig spaces where people are used to move around.
-Images can appear anywhere, not solely in the speaker positions.
-You can place the loudspeakers in convenient positions -not necessarily a square (B-Format or UHJ).
-The mono/stereo compatible hierarchical encoding scheme UHJ allows the transmission of Ambisonic material via two or more channels, offering the maximum effect for a given number of transmission channels.
-Undecoded 2-channel UHJ provides significant “super stereo” effects, comparable to those of other systems.

Ambisonics goes further than stereo in that what it does (to first order) is to sample the acoustic field in such a way that the combination of the signals from all the loudspeakers in the array produces a reconstruction of the original acoustic wave field (both travelling and standing wave components). If a listener puts his head in the sound field, because the wavefronts are similar to the original, the perception of directionality and space should correspond to the original too. It is a “wavefront reconstruction” scheme in the small. The ear signals (crosstalk and all) will be correct if the reconstructed wavefronts are correct. This is just like natural hearing. Increasing the number of loudspeakers in Ambisonics (each fed its correctly-decoded signal) increases the accuracy of the reconstruction and the region over which it holds up.

It is pretty impossible to ask, build and set up either quadraphonic either ambisonics sound system in music venues. In “silence, aircraft noises and harmonies in pain” what I would like to do is to be based in some of these technical notes. From my experience as a listener, I do very much appreciate that listening is also a matter of body beside a sonic and mental movement. The possible thing is to make the audience feel that. So, I decided to vise versa little bit the “directions” of these two sound systems.

I am strongly convinced that sounds that come from behind are offering a “space” to critical audience to listen, feel and hear in a different way. Biologically, the main effects that ear’s pinna delivers to the body goes in the front part of the human body (stomach, chest, forehead etc). Both these systems (especially quadraphonic) are based in the fact that the main sound comes from the front speakers. In this project the heavy sound, the aircraft noises will reproduce and come from the rear speakers in order to create a “whole body listening.” Equality in discrete signals will help on that at different moments and spots during the perfomance.

Architectural acoustics, infrasound, ultrasound, inter space noise control, ultrasonic less lethal weapons (USW, such as “vortex ring gun”) and ITU-R 468 noise weighting are being increasingly developed in ourdays. The sound for me should be no more a simple fact of PA’s, although I totally respect the beauty and the “immortality” of the classic way of listening.

At the end some words about the dissipative action of visual elements on the sonic material. In multimedia’s era it might be “out of order” to deny use visuals in live perfomances. O, yes, indeed it is. The perfomance for me does not have any need to be reinforced by visual aspects in order to make the presentantion more appealing.

There are some needs of possible connections between sound and image, but not here. It is slavishness to route the audience into icons when sound is huge enough to open the gates of alternative experiences. Personally, I felt always under “violence” when the sound part was interesting and I was forced to see icons. Although, there are exceptions, when the context between the optical and the audible is highly tight. Multimedia is a great possibility, but it’s a very “fragile” one to be used in the wrong place or time.

This project is an effort to test the limits of sound gates, to build up a sonic environment where the sound is the major advantage, because it naturally leads to an intense focus on the sound itself.

Posted December 14, 2007 in