Re: our work (fwd)

Darren Kelly (
Thu, 16 Apr 1998 15:25:09 +0200 (MET DST)

On Fri, 17 Apr 1998, David Rodger wrote (cheekily):

> >Attach a smooth pendulum to the
> >MIDI pitch bend controller and you get techno ! (Hardy ha ha :) giggle
> >yoho giggle smurf).
> Sure. The pitch bend value then doesn't change, thus confirming that
> stasis is the main feature of techno music. (Hardy ha ha :) giggle yoho
> giggle smurf).

Sure it changes. You've described Barbra Streisand singing, Davo. Let
x(t) be the pitch offset (since negative pitch doesn't make sense):

d^2 x(t) + omega^2 x(t) = 0 Linearised pendulum equation.

with initial condition x(0)=x0, with x0 not 0. The frequency of the
harmonic modulation of the pitch is then f = omega/2/Pi. You hear:

wee waa wee waa wee waa wee waa wee waa wee waa wee waa

which is boring. If you trigger drums on it as well you definitely
get techno. For large amplitudes you use the non-linear equation
(a sin(x) comes into it), and the period of the modulation becomes
amplitude dependent. The modulation is then slightly more exciting,
but the _period_ of the motion remains constant for closed oscillations,
so you get trance. If you have friction in the system (such as a DJ
holding a finger on a record) you get period variation, i.e. rap.

Now, if you stick a driving term f(x(t),dx/dt(t),...) in (such as a brain):

d^2 x(t) + omega^2 x(t) = f(x(t),dx/dt(t),..) <-creativity

you hear enchanting music like Schoenberg:

wee waa ouch gobble-dee gook womble smidge aha agar zoom giggle...

(Just _imagine_ a dance sequence expressing that)


Darren Kelly | | |
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