of Microprocessors

74 MUSICAL ApPLICAnONS OF MICROPROCESSORS
pressure waveforms could also be applied to the parameter waveform or
envelope. One type of processing that would have an interesting effect is
jiltering of the parameter envelopes. A high-pass filter, for example, emphasizes
high frequencies relative to lower frequencies. The direct effect on the
waveform is to emphasize rapid variations and ignore slower variations and
trends. High-pass filtering of the trumpet solo data, for example> might
produce a caricature of the original playing style. Low-pass filtering of a
parameter has an opposite effect in which short and rapid variations are
smoothed out and slow variations or trends are emphasized. The result might
very well sound as if the performer had become drunk!
Hand manipulation of the parameters, of course, is also possible. One
way to determine how a particular parameter contributes to an overall effect
is to resynthesize the sound with that parameter held constant or set equal to
some other parameter. Statistical analysis of the curves might make it possible
to completely separate two parameters that normally influence each
other. For example, overall loudness and spectrum distribution are related in
trumpet sounds. Loud but mellow notes are not generally possible as are soft
but blaring notes. Conversely, two parameters that normally vary independently
may be made interdependent.
Of course, with a computer-based system, the results of sound analysis
may be stored for later recall or for combining with other analysis data.