[SciPy-User] Accurate Frequency Measurement

David david@silveregg.co...
Tue Nov 30 00:59:29 CST 2010


On 11/30/2010 03:30 PM, Seth Nickell wrote:
> I'm indeed evaluating partials, analyzing some of the interesting
> analog sine tone installations of the composer La Monte Young.

This is a cool application of numpy/scipy ! May I ask which composition 
are you looking at ?

> Young's compositions are so dependent on minutia such as oscillator
> drift that it wouldn't surprise me if some aspects of the effects he
> evokes are dependent on e.g. the amplitude stability of an oscillator.
> Certainly frequency drift is something he utilizes.

Sinusoidal are pretty weird to human hear - amplitude/frequency 
perception does not always correspond 100 % to their signal definition 
(louder sinusoidal may be perceived as frequency changing ones IIRC).

You may want to look at something like CLAM (http://clam-project.org) to 
analyse those signals if you want to track frequency changes. I believe 
they have some python bindings.

That being said, I doubt you will be able to obtain 1/100 Hz precision 
as soon as you start looking at unstable frequencies, especially since 
the oscillator themselves don't have that precision, depending on what 
kind of hardware was used (would be hard to do with conventional analog 
oscillator, I guess).

Please keep us posted !

cheers,

David


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