The Phase Vocoder as a Musical Instrument



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The Phase Vocoder as a Musical Instrument

When a synthesis program becomes real-time, it becomes a musical instrument, and when a computer program becomes a musical instrument, the operator becomes a performer. The ergonomics of a musical instrument are highly complex, but from the context of previous uses of this algorithm in computer music, there are clearly some core areas which must be covered: pitch transposition, which is a change of pitch of a sample without a change in its duration; rate of playback, which is a stretching or compression of a sample in time without any change in its pitch; and timbral morphing, where one sound changes smoothly into another as do pictures in video morphing.

This version of Sculptor permits independent control over pitch and rate of playback in real time even on very modest computing platforms, and will act as a test bed for more advanced algorithms on faster platforms. It was initially developed on a 386DX40 without a floating point coprocessor, and could still make a fair attempt at real time synthesis at 8000 samples per second (voice telephone quality).



N J Bailey
Tue Oct 13 17:55:45 BST 1998