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scalesAlternative Tuning and How We Hear

RHYTHM

Recall the idea of a harmony template that serves as a framework for chord structure. It's possible there is a a second, low frequency template used by the brain to perceive rhythm. It may be similar to the pitch template, yet I'm certain of one difference: in the rhythm template, the phase of the frequency matters. The common pattern of bass drum on beats 1 and 3, with the snare on beats 2 and 4 can be viewed as harmonics of the fundamental.

If we consider the fundamental frequency's period to be one measure, the bass pattern here is 2 x the fundamental. For the first example the snare is "in phase" with it. 
snare  / . . .   . . . .   / . . .   . . . .
bass   / . . .   . . . .   / . . .   . . . .
listen(the pattern is repeated four times)

We can shift the timing of the snare out of phase 180 degrees. Together the bass and snare are effectively 4 x the fundamental. 
snare  . . . .   / . . .   . . . .   / . . .
bass   / . . .   . . . .   / . . .   . . . .
listen(the pattern is repeated four times)

Here we use another sound to explicitly play the 4x harmonic. 
tamb   / . . .   / . . .   / . . .   / . . .
snare  . . . .   / . . .   . . . .   / . . .
bass   / . . .   . . . .   / . . .   . . . .
listen(the pattern is repeated four times)

Now shift it out of phase 180 degrees. All of these considered together are like 8 x the fundamental. 
tamb   . . / .   . . / .   . . / .   . . / .
snare  . . . .   / . . .   . . . .   / . . .
bass   / . . .   . . . .   / . . .   . . . .
listen(the pattern is repeated four times)

Now let's consider the harmonic that is 3 x the fundamental. Played along with the bass at 2x, we get a three against two pattern. 
bongo  / . . . . .   . . / . . .   . . . . / .   . . . . . .
bass   /  .  .  .    .  .  .  .    /  .  .  .    .  .  .  .
listen(the pattern is repeated four times)

We can shift the phase by 1/12 to get a different rhythm. 
bongo  . . / . . .   . . . . / .   . . . . . .   / . . . . .
bass   /  .  .  .    .  .  .  .    /  .  .  .    .  .  .  .
listen(the pattern is repeated four times)

If we increase the bass to 4x, we get a three against four pattern. 
bongo  / . . . . .   . . / . . .   . . . . / .   . . . . . .
bass   /  .  .  .    /  .  .  .    /  .  .  .    /  .  .  .
listen(the pattern is repeated four times)

We can also phase shift the 3x pattern to get a different rhythm. 
bongo  . / . . . .   . . . / . .   . . . . . /   . . . . . .
bass   /  .  .  .    /  .  .  .    /  .  .  .    /  .  .  .
listen(the pattern is repeated four times)

Also, we could split apart the 4x into two 2x beats, using the bass and the snare, shifted 180 again. 
bongo  / . . . . .   . . / . . .   . . . . / .   . . . . . .
snare  .  .  .  .    /  .  .  .    .  .  .  .    /  .  .  .
bass   /  .  .  .    .  .  .  .    /  .  .  .    .  .  .  .
listen(the pattern is repeated four times)

Higher harmonics can be used, such as five against four and three.
same as previous example
plus a 5x tambourine
which can't easily be shown here
listen(the pattern is repeated four times)

I think the rhythm template time length might actually extend out into many seconds. Lots of songs have periodic patterns of four measures, or more. Twelve bar blues is a great example of a very long template time. The overall structure of songs (e.g. A-B-A-C-A-B) might fit into this template as well.

This document is ©2003 by Bill Grundmann.

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