[sdiy] Alex sings Geddy with formant envelope synthesis?

Marc Jordan MJordan at SigmaTel.com
Wed Aug 21 21:34:15 CEST 2002


I just saw Rush in Houston & San Antonio & noticed that Alex was singing
some backup vocals on the new Rush tunes. The cool thing was that I was
hearing Geddy's voice. I doubt that he was just lip syncing because they've
never been ashamed of or hid the fact that they trigger samples big time
live.

I'm guessing that they were running his voice through a DSP box that applied
formant envelopes to approximate Geds vocal characteristics. Does anybody
know if this is being done in real-time these days? I took a synth class a
number of years ago and did some experiments with formant envelopes and you
would be surprised how good they work. Probably good enough for background
vocals in a loud-as-hell rock setting. I don't remember all the details of
the computational complexity: a little bit of off-line FFT analysis of Ged's
voice to build up the envelopes to store away, then live you'd have to FFT
short bits of Al's vocals, apply the envelopes, then convert back to the
time domain. Hardware is beefy enough these days to do it real-time I
imagine. Heck, it's probably really not that much of a MIPs hog.


Marc Jordan
Embedded Audio Software
SigmaTel, Inc
3815 South Capital of Texas Hwy, Suite 300
Austin, TX 78704
Telephone: 512-381-3700




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