"Ryan" wrote in message
om...
"Paul Stamler" wrote in message
...

I think one of the things you'll find, investigating these real-world
sounds, is that most of them differ drastically from the sound made by
most
musical instruments in that they are inharmonic; in other words, musical
instruments produce sound consisting mostly of a fundamental and
harmonics,
at integer multiples of the fundamental frequency. Real-world noises, to
a
great extent, have mixtures of frequencies that aren't integer multiples
of
one another.

This is something I've always wondered about. I thought everything
obeyed the 1st harmonic, 2cnd harmonic, etc., rules. Is it possible
for a sound to have no overtones? I thought that even computer
generated sounds that have no harmonics on screen, produce them
automatically when they come out of the speaker. I thought the
harmonic series was just part of the physics of sound. Yes, real
world sounds often contain dissonant and un related intervals, but if
we broke down the overall sound to a set of sounds, wouldn't these
sounds in themselves produce the natural overtones?

Not necessarily. Many noises contain a mixture of frequencies not at all
harmonically related. For that matter, sometimes even musical instruments
produce a sound that isn't perfectly harmonic -- in other words, the
harmonics aren't exact integer multiples. One of my guitars at the moment
needs its strings changed; they're no longer perfectly cylindrical (there
are dents in the windings where they go over the frets), and the harmonics
aren't quite perfect multiples of the fundamental anymore. Which is why it
sounds like crap, of course, and will continue to do so until I get off my
duff and change the strings.

Another example: play a guitar through a fuzzbox or an amplifier craniked up
enough to distort. Play two strings and, along with the harmonic series of
each individual note, you'll get a whole raft of intermodulation products
not part of that harmonic series at all. That's the fuzz.

Anyway, back to non-musical noises. I remember having to clean up a
recording made in a room with a large HVAC blower outside. It had a lot of
different frequencies in it, most of them not related to each other by any
simple ratios. Along with that was a heap of white noise.

No, not everything obeys the harmonic rules.

Peace,
Paul