Thoughts on Sound Diffusion I

I think that one of the nice things about sound diffusion that struck me when the concept was first introduced is the conceptual simplicity of it. We spend a lot of time and thought within the world of music technology trying to invent completely new ways of doing things – be they innovative instrument or synthesis design, new methods of signal processing, alternative controllers and cross-media practices. As a result it is refreshing to use an approach that is really not much different from the principle of multi-track recording – albeit in a ‘reverse-engineered’ manner – to manipulate and spatialise sound.

Taking stereo audio channels and spreading them around a variety of speakers in an auditorium also emphasises the importance of acoustic space. Having memorised a track in its normal stereo configuration and getting to know its intricacies this way, and then placing it in all corners of a hall can greatly transform the work. You start to hear the track in completely new ways – indeed it can become a new piece altogether. In a way, it can be something like a process of live re-composition, or at least remixing of a piece.

This also provides a simple way in which you can ‘play the room’ in which you are listening to the piece. The room’s acoustic becomes a significant factor in the process of diffusion. How this is manipulated and played upon by the diffuser is part of the enjoyment of the experience. It also means that the role of the audio engineer in the production of the recorded music is rendered slightly less important, as the previously definitive recording of a work is now open to reinterpretation.

The variable acoustic responses of different sets of speakers is also striking when doing a diffusion. This is a feature that can be exploited by the diffuser to creative effect. In particular, in our experience, the upper speaker pair in our six channel array is of significantly lower acoustic quality than the two Bose pairs. Their frequency response tends to be significantly in favour of the higher end of the frequency spectrum. This has an effect of emphasising the closeness of the sound – which actually provides a great contrast with the boomier characteristic of the auditorium. This contrast, particularly when listening to ‘smaller’, less reverberant sounds can be used to great effect.

Of course, not every piece of music ever written is ideal for sound diffusion. This much has become apparent in our first few experiments. Obviously, the technique has a natural affinity to the musique concrete end of the musical spectrum. I think the reason for this is that this genre places the emphasis on the quality of individual sounds, and often exploits a wide variety of different sounds. The other significant factor in musique concrete is there is often quite a deal of space (silence) within the music. Musical space (not spatialised space) is really helpful when doing a diffusion, as it gives you a chance to rapidly shift the position in acoustic space. This allows a point of tension to be created as it becomes uncertain where new sounds will be heard. Also, sounds the listener is accustomed to might begin to appear in a completely new context. Having said this, it is also a good effect to ‘ride the levels’ of the different channels for a continuous sound within the musical texture and bring it in and out of various spatial configurations.