crystal sounds

In yesterdays digest, Ray Tomes asked me to clarify some about the
techniques used in the "Sound of Crystals" article...

..can you please explain how you determined what frequencies to
play at what time. I imagine that the crystal output (slowed down)
is a bit like sitting on the keyboard and staying there so you need a
way to seperate the notes.

There are many ways that one can utilize spectra (such as that of
the morphine cyrstal) to generate sound. The two techniques that I
have explored are:

(1) using the spectrum to define a single "sound" -- in this approach I
generated about 2 seconds of sound by mapping the x-ray
frequencies into audio frequencies. This was then transferred to a
sampler, and played like any other sampled sound, in any desired
tuning.

(2) using the spectrum to define a "scale" -- in this case, each x-ray
frequency of the crystal is mapped to a separate key of the keyboard
(and of course, also mapped down into the audio range). Using a sine
wave sample then allows the "complete" sound to be played by
pressing all the keys simultaneously.

Thus, in both cases, I "composed" the pieces by improvising on the
keyboard. In the first case the crystal provides the basic "sound"
while in the second case it provides the "tuning".

Greg Taylor then said some nice things (blush) and continued...

Just out of curiousity, what other XRD stuff sounded interesting?
Can one generalize? I wouldn't mind trying to map an essential
oil like Melissa, which I could then collide with the Allman
Brothers tune of the same name....

Well, our original idea was to try and develop a kind of "auditory
crystallography" in which you might use the ear to hear patterns in
the x-ray diffraction data that the eye doesn't readily see. What we
ended up with was a way of generating some interesting sounds (and
scales, I suppose). The problem was that we were never really able
to convince ourselves that we could reliably distinguish the sounds of
various materials. Of course, every substance sounded somewhat
different, but the differences weren't something that was easy to
describe or remember. So, sorry Greg. We were never able to discern
any real patterns in how various materials sounded, nor were we
able to generalize enough to predict if something would sound
"interesting" (whatever that means) or not. Thus, it would be
impossible to predict if linguistic similarities (like your oil and an
Allman Brothers song) would be acoustically compatible. Nor even if
the sound of oil would be slick.

[The other, perhaps larger issue that still remains largely unexplored
is the issue of the effect of details of the mapping. I once started a
paper on this, but never finished].



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