To produce the masking threshold from the spread function and the masker,
we need to know the *tonality* *t*(*z*) and the spreading function
*SF*(*z*) of the masker.
After an idea taken
MPEG-1 layer I [6], the following model for masking threshold
*M*(*z*) is used:

where is the frequency in Bark for the masker, *z* is the masked
frequency in Bark and is the power of the masker in dB.
The functions *k*(*t*) and *l*(*t*) are experimentally found as a linear
combinations of constants for pure noise and pure tones:

Sat Mar 7 16:27:43 PST 1998