ZPI is an
abbreviation of Zygotech
Polynomial Interpolation and is a propetriary
technique invented by
Casio in order to
generate better and more
filtered sounds on their newer
synthesizers and
keyboards.
The
technique involves smoothing out the
jagged edges in the wave of a
digitally recorded sample, thus
reducing the digital
noise levels and giving an overall higher
fidelity of the sound.