DAU1997 - Linear filtering for monaural masking (improved)

Usage:

[outsig, fc] = dau1997(insig,fs);
[outsig, fc] = dau1997(insig,fs,...);

Input parameters:

`insig`	input acoustic signal.
`fs`	sampling rate.

Output parameters:

`outsig`	output signal
`fc`	center frequencies [Hz]

Description:

dau1997(insig,fs) computes the internal representation of the signal insig sampled with a frequency of fs Hz.

[outsig,fc,mfc]=dau1997(...) additionally returns the center frequencies of the filter bank and the center frequencies of the modulation filterbank.

The model consists of the following stages:

a gammatone filter bank with 1-erb spaced filtes.
an envelope extraction stage done by half-wave rectification followed by low-pass filtering to 1000 Hz.
an adaptation stage modelling nerve adaptation by a cascade of 5 loops.
a modulation filterbank

Any of the optinal parameters for auditoryfilterbank, ihcenvelope and adaptloop may be optionally specified for this function. They will be passed to the corresponding functions.

References:

T. Dau, B. Kollmeier, and A. Kohlrausch. Modeling auditory processing of amplitude modulation. I. Detection and masking with narrow-band carriers. J. Acoust. Soc. Am., 102:2892--2905, 1997a.