Reply to Aaron and a new (old) piece

Hi Aaron, thanks for the kind words about "Exomusicology."

Aaron wrote:

> There are several extremely unique and special tracks to be found on this
> disk. Notable is 'Over Venus' for its beautifully alien take on overtones and
> drones. An instrument the liner notes calls a 'Klein trumpet' has a strange
> disembodied sound to it that is quite striking. 'When everything was
> simultaneous' and 'Temporal Consciousness' use speech elements in a uniquely
> strange and spectral way. This listener has heard nothing quite like it.

OK. I admit -- it's not really a trumpet made from a Klein bottle.

It started as a pretty generic flute sample (I can't remember whether
it was an "alto flute" or whether I just didn't use the upper octaves).
Anyway, I played the piece (about 30-40 seconds of a sustained droney effect)
in an overtone tuning using a WX-5 wind controller.
It sat around for quite a while because it didn't really sound all that good.

Then I was developing some FFT based routines which do the following:
(1) break the piece up into (roughly) 1/2 second segments (sometimes overlapped).
(2) take the spectrum (FFT)
(3) locate the largest n peaks (n might be 2 or 5 or 20, depending on the source).
(4) move those peaks to the nearest harmonic series
(5) invert the changed spectrum back into a time signal

So - what you hear in "Over Venus" is the same 30-40 seconds repeated
several times (cut and paste) but each time using a different set of parameters
in the routines (e.g., different segment sizes, different n, different overlaps).

You hear all the high tinkly stuff? All of that is unintended byproducts or artifacts of
the algorithm. Very often when you do analysis/resynthesis methods, you get weird
tinkley and jangley things going on... this is especially true when the length of the
analysis segments is large (like the 1/2 second used here). I've actually spent a
ridiculous amount of time attempting to remove the artifacts from the process,
but in this case, I decided that the artifacts themselves were quite cool.

In fact, this is the same kind of algorithmic manipulation used in both
"Temporal Consciousness" and "When everything was Simultaneous" though of course
it was applied to vocal based samples (and a didgeridoo sample) rather than
the flute. The artifacts are quite striking -- in both of these what happens
is that when you do the FFT segmenting and change the phase, it
scrambles up the signal. Using different size segments changes the scrambling from
rapid to an almost stuttering effect.

As I was writing this message, I remembered another piece using (more or less)
the same technique. It's called "VarMixUp" because it's all variable and mixed up (this is a
"working title"). For a variety of reasons, "VarMixUp" didn't make it onto
Exomusicology. Anyway, you can download it at:

http://www.cae.wisc.edu/~sethares/VarMixUp.mp3

Enjoy!

--Bill Sethares