How do the circuits they use on TV to keep the audio pitch the same when
they speed up the tape work? I know they do that so that can shorten the
program and squeeze in more commercials. I remember watching a show once and
after a commercial break, they didn't reengage the circuit and everybody was
Alvin the chipmunk.
At any rate, suppose you played the audio twice as fast, but used a similar
circuit to restore the original pitch. Then you took that processed audio
and played it at half speed, this time with no pitch correction. Wouldn't
that compress each frequency to half it's original value?