The tonality of a frequency bin is estimated by looking
at the predictability of the *phase* and *magnitude* of that
Fourier coefficient. The predictors are defined as follows:

The phase is thus linearly extrapolated from two former time instances, and
magnitude is simply assumed to be the same as last. This gives no
prediction error for *one* stationary sine within the frequency band.
The tonality is then estimated from the maximum prediction error of the
last two phase values and the last magnitude:

where and
. This model gives
a weighted average *t* of about 0.9 for highly tonal sting music,
and 0.3 for white
noise. Of course the parameters in the masking threshold (section
3.2.5) estimation are
adapted to these (non-ideal) values.

Sat Mar 7 16:27:43 PST 1998