# SIG_NOTCHEDNOISE - Generates a notched-noise-type masker

## Usage

outsig = sig_notchednoise(fs,fc,dur,L,bw,delta);
outsig = sig_notchednoise(fs,fc,dur,L,bw,[deltaL deltaR]);

## Description

`outsig = sig_notchednoise(fs,fc,dur,L,bw,delta)` generates a notched-noise
masker with duration `dur` (in sec) and overall level `L` (in dB SPL)
with a sampling rate of `fs` Hz. The deviation from center frequency
`fc` is symmetric and is given by `delta` such that the stopband is
`[fc-delta*fc fc+delta*fc]`. The left and right noise bands have a
bandwidth of `bw*fc` in Hz. If `delta=0` then a broadband noise is
returned.

`outsig = sig_notchednoise(fs,fc,dur,L,bw,[deltaL deltaR])` generates a
notched-noise masker with an asymmetric configuration. `deltaL` and
`deltaR` denote the left and right deviations from `fc`, respectively.
In this case the stopband is `[fc-deltaL*fc fc+deltaR*fc]`.

This notched-noise-type masker was used in psychoacoustical studies
investigating the auditory filters' shape (the original method is
described in Patterson, 1974). The noise is composed of two noise bands
of width `bw` and a stopband centered at `fc` with a deviation from `fc`
given by `delta`.

## Examples:

The following shows the spectrum and a spectogram of a typical notched
noise masker used in the Patterson study:

fc = 4000;
fs = 16000;
dur = 1;
L = 100;
bw = .5;
delta = .2;
outsig = sig_notchednoise(fc,fs,dur,L,bw,delta);
figure(1);
plotfftreal(fftreal(outsig),fs,100);
figure(2);
sgram(outsig,fs,80);

## References:

B. Moore, R. Peters, and B. Glasberg.
Auditory filter shapes at low center frequencies.
*J. Acoust. Soc. Am.*, 88(1):132--140, 1990.

R. Patterson.
Auditory filter shape.
*J. Acoust. Soc. Am.*, 55:802--809, 1974.