Pitch & Frequency

media at mail1.nai.net media at mail1.nai.net
Sat Jan 17 18:02:51 CET 1998


>Anyway, "pitch" refers to the note of the musical scale that the human
>ear/brain combination percieves. "Frequency" refers to the reciprocal of
>the repeated waveform pattern measured in seconds.

Sounds good to me.

>here are many complex modes of vibration
>going on that the are not all integer ratios to each other.

Right.  There are various "partials" that have non-integer ratios to the
fundamental, and events random enough to be considered noise (especially in
percussion instruments like a piano), and tonal elements whose frequency
have no dependance on the fundamental (such as the resonances of the space
and cabinet).

(You probably already know all this already, but I feel like typing.)

I believe its the existence of these components is what makes pitch
shifting without audible artifacts so difficult -- no matter how it is
chunkified.

>This confuses the human ear somewhat, so that the overall effect integrated
>by our senses results in a musical note detected that does not always
>match up with what an oscilloscope says we "should" be hearing.

Actually I think it would be more fair to say it confuses the test
equipment!!  Humans have more intelligence than a DSO -- our minds can
perceive a melody through the worst clamor.

>Also on the Leslie thread - I concur with the other observations, except
>that there are no centrifugal forces on the voice coils (at least not in
>the 127/147). Another tip - when demonstrating your Leslie to curious
>onlookers, try not to point at the treble horn when tremolo mode is on!

Sorry, I was being silly :)   However, I remember when I was kid I did
sound for this band who had a cabinet with two rotating speakers.  One
speaker was a horn tweeter and the other was a huge bass driver in a
semicircular sub-cabinet.  I have no idea who built it.  Both drivers spun
on the same axle (I don't remember if they were on the same side or not),
but I remember needing two microphones (one mounted above the other).  So,
I was thinking about that enormous woofer flopping around at some
incredible speed.

Frightening, isn't it??

PEACE OUT :)
MARK






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