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:
