I'm looking to find out more about writing some software that will use
traditional classical instruments to emulate "natural" or "non musical
sounds." The software will perform some type of analyses on an audio
file, I imagine FFT would be used at some point, but the problem with
FFT is that it only tells you what "perfect" or pure sine wave based
frequencies are present in a sound. Besides the flute, not much else
in an orchestra has anything close to a sine wave output. After this
analysis is done, the software will look through a library of sounds
made by traditional instruments. These sounds will include every
noise and playing style every traditional instrument can produce. The
software will then juggle the sounds around at various dynamic levels
in various rhythms and etc until it comes up with the closest
combination to the original sound. Perhaps a car engine sound file
would yield three Double Basses, a flute or two in very quiet
irregular rhythms, and maybe a horn would be involved during gear
changes. I might not have to tell you that Gyorgy Ligeti's
"Atmospheres" and his "Mechanical Music" served as the chief
inspiration for this idea.

Has anybody ever heard of anything like this, or know where I might
start to look for info on this subject? I'm not looking for
programming help, but rather, help with setting up the math. Are
there any scientific communities online that I could point my
questions to? Any books on this type of thing. I've heard Csound
might work for this. I thought Csound was for composing, not for
analyzing existing sound files. I can't seem to come up with the
right keywords to get anything out of Google, but I hoped someone here
might be able to put me on the right path.