Bill Sethares' Analysis of Detwelvulate! Track 3

Ooops. I meant to send this to the list, not just to Paul.

Actually, listening again to the opening chord, I hear something a little
different. The opening minor-third chord is about 3 seconds long before the
first melody note enters. There is some sort of square, on/off change (no
intermediary values) that occurs about once a second during that time. During
that first second-long period, I hear something that sounds to me like a classic
beat, but it vanishes after that first second-long period.

But anyway, check out Bill Sethares' analysis below.

By the way, it sounds different depending upon where and at what angle I
place my head within the room. That beat during the first second-long period
seems almost inaudible when I have my head between the two speakers, but is
clearly audible when I have my head turned 90 degrees so that both speakers are
toward my left ear.

For you folks doing sample looping, that's something I've found to be very
valuable: Don't declare a loop to be clean without moving and tilting your head
relative to the monitor speakers. Some flaws in some rooms can easily be
rendered inaudible when your head is at one angle or another.


--------------- Forwarded Message ---------------

From: Gary Morrison, 71670,2576
To: PAULE, INTERNET:ACADIAN/ACADIAN/PAULE%Acadian@mcimail.com
Date: 10 Jul 1996 , 7:16 PM

RE: Darreg Disc Error: track 3 mislabelled

> Not only does that minor third sound wide from just, but it also beats just
> under 3 times per second. Gary, maybe you should listen to it on a different
> stereo system, this beating is not hard to hear.

I definitely heard something changing at the low-mid frequency range, at
about the rate you mentioned, but it didn't sound like a beat to me. I say
"didn't" because of some results Bill Sethares came up with.

He did a mathematical analysis of a certain passage, and the frequencies
present drew two conclusions I found surprising:
1. Two pitch changes in a chromatic run were 48 cents and 52 cents. It seems
likely therefore that it's not in 17, 19, nor 22, but in quartertones.
2. The timbre, despite its brightness, consisted of only of two partials an
octave apart. I don't recall what he said were the relative weights.

As for the beat, I suppose that that change we both hear could be a beat
after all. The tone was bright enough that I expected it would have major wads
and wads of high-harmonic content, in which case the beats would sound like
typical phaser/flanger effect from a Tomita album. It would be a horrendous
comb-filter sweep - FAR less subtle than that fluctuation you pointed out.

But knowing that the tone is really just a couple of partials (and apparently
low ones), then yes, that probably is exactly what such a waveform's beat would
sound like.



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