GAMMATONE - Gammatone filter coefficientsUsage:
Description:GAMMATONE(fc,fs,n,betamul) computes the filter coefficients of a digital gammatone filter with center frequency fc, order n, sampling rate fs and bandwith determined by betamul. The bandwidth beta of each filter is determined as betamul times AUDFILTBW of the center frequency of corresponding filter.
GAMMATONE(fc,fs,n) will do the same but choose a filter bandwidth according to Glasberg and Moore (1990). The order n can only be 2 or 4. If the order is 4 then betamul is choosen to be 1.0183 and if the order is 2 then betamul is choosen to be 0.637.
GAMMATONE(fc,fs) will do as above for a 4th order filter.
If fc is a vector, each entry of fc is considered as one center frequency, and the corresponding coefficients are returned as row vectors in the output.
The inpulse response of the gammatone filter is given by
To create the filter coefficients of a 1-erb spaced filter bank using gammatone filters use the following construction
[b,a] = gammatone(fs,erbspacebw(flow,fhigh));