Posted by Ian Easton on April 06, 2003 at 08:10:20:
In Reply to: Re: Re: Re: Re: multiphonics for tuba??? posted by ?????? on April 05, 2003 at 22:04:50:
It is perfectly possible to produce several tones from the same vibrating source by changing the size of the resonating chamber (ie mouth/throat).
Every note (apart from a pure sine wave) has an overtone structure, and by emphasising an overtone within a note one can hear a 2nd note clearly. Changing the emphasised overtone within that note gives the ability to sing/play scales/tunes above a single note. Try changing the frequency cut off on an old analog synthesizer (with resonance up full), or singing "WWWHHHHAAA" very slowly with an open throat (works best for me on low notes with a microphone pointing straight up).
Note that this is quite different to a change in pitch.
Further frequencies can be 'coaxed' from 2 or more notes: the addition of the frequencies and their difference can also be heard.
If a performer wishes to use recording or sound reinforcing equipment as creative tools then aliasing effects (research the Nyquist Theorem) can give the semblance of multiphonics too (I personally wouldn't call this cheating, but some may!)
If !!!!! doesn't believe this he/she should research Tuvan throat singing, the Harmonic Choir, wolf tones etc before exposing his/her ignorance, albeit anonymously.
Ian