Re: streams and groups (Sigurd Saue )

Subject: Re: streams and groups
From:    Sigurd Saue  <sigurd.saue(at)VOXELVISION.NO>
Date:    Mon, 14 May 2001 21:23:58 +0200

Dear list,

being merely an engineer I probably should stay out of this very interesting
discussion. But the subject is very relevant to my Ph.D. work so I hope you
forgive my display of ignorance.

I work on sonification of spatial data with a focus on how to map space into
the temporality of sound, preferably using everyday listening as a model. In
particular I've been trying to find perceptual time scales that are
relevant. I ended up with four levels, that could loosely be described as:

1. Sub-unit (the temporal variations that we perceive as timbre).
2. Unit (temporal variations within a stream)
3. Group (temporal variations between streams)
4. Global (the totality of temporal events, not perceived as variation)

I'll take a bird call as an example:
The variations within the single chirp (sub-unit) characterizes the timbre.
The chirps are organized into a pattern on the unit level. The same bird
repeating the pattern a little later, or another bird singing represents
variation on the group level. The totality of bird calls and other nature
sounds constitute the ambience which is not perceived as changing at all
(unless we make an effort of conciously analyzing it).

I'm aware of some writings on time scales in music (e.g. the 9 time scales
of Curtis Roads), but I find that these 4 levels are satifying in
representing everyday listening. Am I way off track?

Any comments appreciated.
Sigurd Saue

> A musical "note" (in the auditory sense) is an unit within a
> melody; a single footstep is a unit within a sequence of steps.
> A unit is a perceptual entity that is intended by Mother Nature
> to correspond with a single "event" in nature (a single step of
> an animal; a single activation of a piano key, a chirp of a
> bird).

> Perhaps the word "group" should be used to mean a cluster of
> units within a stream -- perceived as a cluster due to the fact
> that the acoustic differences are greater between the groups than
> within the groups, or to the fact that there exist
> discontinuities or silences that are greater between successive
> groups than between the successive members of the same group.