From: Aaron Ximm <>
> Re: filtering for pitch,
> I've done some composition based on the selective filtering of different
> sources (eg, wave sound, or complex soundscapes) by pitch, but instead of
> using tubes in the environment, I did processing in post using FFT filter=
s
> I created to pull out specific frequencies. (If you're unfamiliar with FF=
T
> filters, think: many-thousand-band graphic EQ).
Not only many thousand band, but as implemented over various filters
almost infinite band shape.
> Eg, to pass only that part of a given recording that's pitched A, I would
> pass a narrow band at 400 Hz, 800 Hz, 1600, etc. up the octaves... my
> software, Samplitude (PC only) allows you to "draw" a curve by hand; I'd
> draw bell curves centered around each pitch. I now have a good library of
> them at useful pitches, for well-tempered diatonic scale and the gamelan
> slendro and pelog scales.
The Equium plug in that I mentioned earlier would make this even easier.
It has built in harmonic (4 or 8 step) filters, that can be adjusted in
many ways. You can move one of those through the frequencies while
listening to the effect to find the "ideal" frequency. Which won't
necessarily be right on a specific musical pitch. Since the harmonics
are all one filter, they maintain the proper relationships while being
moved. Surprising how you can often pick out some background sound and
move it to the foreground that way, much better than just a single
frequency emphasis. I definitely will play with that more to see how
practical it is.
Equium's harmonic filters make good hum filters too.
>
> (I've also done some work "stacking" various filtered versions of specifi=
c
> single recordings to pull out triads, and used shelving EQ downstream to
> change the "spelling" of the chords if you will.)
Again, in Equium you have a whole bunch of filter types, and can stack
large numbers of them if necessary. In mixed types. And, of course save
a stack for future use. The analogy to a multi band equalizer is way too
simplistic.
Walt
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