Thoughts on Sound Diffusion IV

My interest in sound diffusion is in its use as a sound parameter for compositional manipulation. Traditionally, the primary parameter[1] has been pitch, with volume and timber close behind. Over time, a rich system of language has developed around the use of pitch in music. Modes, scales and harmony are our method of creating organised, ineligible sound from the continuous choices in pitch from (almost) 0 Hz to 20kHz. Likewise, volume is organised into categories such as pianissimo, mezzo forte and sforzando[2], and as composers we (try to) understand how to use volume to support a composition.

As a compositional parameter, though, diffusion is probably not as well understood. Avoiding the temptation to grandstand about the opportunity to create new knowledge, I think this relatively unexplored parameter provides a kind of freedom to discover a language without the legacy of an established body of knowledge. So far we tend to use diffusion somewhat crudely - mostly to support a sense of depth (more distant sounds are made to be more diffuse). Of course, this is due to the positive correlation in the natural acoustic world between diffusion and distance.

Must we be limited to this though? What if we manipulate diffusion to support the dynamics of a composition itself? In an auditorium filled with speakers (and listeners!), the temptation to correlate the number of speakers to aural size may be difficult to resist, but what about an inverse correlation? For example, one might establish a sonic language of quiet, spatially diffuse sound (perhaps using grain clouds sourced from an outdoor recording). Following this with a direct sound (such as a sawtooth wave at 1kHz), whilst simultaneously collapsing the spatial field down to a single speaker could produce quite an arresting effect. Of course, there are many more possibilities worth exploring.

-Kim.

[1] I'm not counting time as a parameter for the purpose of this discussion, as it behaves differently to these parameters of sound.

[2] Or more recently, K-20/RMS, K-14/RMS and K-12/RMS.