[sdiy] Re: What is chaos?

[Philippe Gauthier]

John Mahoney wrote:
> At 10:37 AM 2/12/2007, fmg wrote:
>> I've googled for hours and am more confused than before. I'm not
>> searching for synth patches or module schematics, just an
>> aproximate definition of such thing (in a musical context). I'm
>> deeply in the dark in these matters.
>> Personal opinions highly welcomed.
> 
> Fabio,
> Look up "aleatoric music", which is sometimes called "chance music", and
> you'll find plenty of info.
> 
> In synthesis, a chaos/aleatoric/chance patch will usually employ some
> kind of noise generator(s) -- that could be analog and/or
> digitally-generated noise, also called random voltages. The Buchla term
> is "uncertainty".

In fact, chaotic behavior appears random, but is deterministic. In
physics, a deterministic system means that the behavior of the system
is defined by initial conditions and is not random.

On the other hand, we say that complex random processes have an
appearance of chaos. In familiar language, chaos simply means complete
disorder. It is arguable that chaos, in the physics meaning, is less
chaotic!

> Another way to create chaos is by mixing together a few LFOs that are
> not synchronized together in any way. Even better is to use at least one
> voltage-controlled LFO, and using noise (random voltages) or mixed LFOs
> to modulate the frequency of the VC LFO.
> 
> Feedback loops are often used in these patches. Like, signal 1 modulates
> signal 2 which modulates signal 3 which modulates signal 1.

Suppose you have three VC LFOs and you patch them together in such a
loop. At some point in time, you set the state (initial conditions) of
all the LFOs (for example, by using precisely timed sync signals.) You
listen to your creation... You then set the state of all the LFOs to
the same initial conditions. In theory, you should hear exactly the
same patterns both times.

If you take a good noise generator, you never will be able to
reproduce a sequence.

In music, chaos is used mostly for it's ability to produce interesting
sequences. For example, chaotic systems will tend to oscillate in a
rhythmic pattern. With noise, patterns occur randomly and so do not
usually repeat. Producing sound with noise is easy and adds complexity
to the music.


-- 
Philippe Gauthier <philippe.gauthier at deuxpi.ca>
http://www.deuxpi.ca/