E-Mu Planet Phatt Operation Manual page 55

PROGRAMMING BASICS
This is the essence of the Z-plane filter. Through the use of
interpolation, many complex parameters are condensed down into
one manageable entity.
Consider, as an example, the human vocal tract, which is a type of
complex filter or resonator. There are dozens of different muscles
controlling the shape of the vocal tract. When speaking, however, we
don't think of the muscles, we just remember how it feels to form the
vowels. A vowel is really a configuration of many muscles, but we
consider it a single object. In changing from one vowel to another,
you don't need to consider the frequencies of the resonant peaks! You
remember the shape of your mouth for each sound and interpolate
between them.
Filter morphing can be controlled by an envelope generator, an LFO,
modulation wheels or pedals, keyboard velocity, key pressure, etc. The
filter Fc parameter controls morphing on certain Planet Phatt filters.
The Q parameter on the Planet Phatt filters can only be changed at
note-on time but can control various parameters such as boost/cut and
mouth cavity size and of course, resonance or Q.
Chapter 4: Programming Basics 47