THE AUDITORY MODELING TOOLBOX

Applies to version: 1.4.0

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BREEBAART2001 - Binaural masking level differences

Usage:

[ei_map, fc, outsigl, outsigr] = breebaart2001(insig,fs);
[ei_map, fc, outsigl, outsigr] = breebaart2001(insig,fs,...);
[ei_map, fc] = breebaart2001(insig,fs);
[ei_map, fc] = breebaart2001(insig,fs,...);

Input parameters:

insig input acoustic signal.
fs sampling rate.
tau characteristic delay in seconds (positive: left is leading)
ild characteristic ILD in dB (positive: left is louder)

Output parameters:

ei_map EI-cell representation
outsigl internal monaural representation of the left ear
outsigr internal monarual respresnetaion of th right ear
fc center frequencies of the filterbank

Description:

breebaart2001(insig,fs,tau,ild) computes the EI-cell representation of the signal insig sampled with a frequency of fs Hz as described in Breebaart (2001) of the signal insig sampled with a frequency of fs Hz. The parameters tau and ild define the sensitivity of the EI-cell.

The input must have dimensions '[time x left/right channel x signal no]'.

[ei_map,fc]=breebaart2001(...) additionally returns the center frequencies of the filter bank.

[ei_map,fc,ml,mr]=breebaart2001(...) additionally returns the center frequencies of the filter bank and the internal monaural representations.

The Breebaart 2001 model consists of the following stages:

  1. an outer and middle ear transfer function
  2. a gammatone filter bank with 1-erb spaced filters.
  3. an envelope extraction stage done by half-wave rectification followed by low-pass filtering to 770 Hz.
  4. an adaptation stage modelling nerve adaptation by a cascade of 5 loops.
  5. an excitation-inhibition (EI) cell model.

Parameters for auditoryfilterbank, ihcenvelope, adaptloop and breebaart2001_eicell can be passed at the end of the line of input arguments.

Examples

The following code sets up a simple test example for the binaural output:

% Setup parameters
fs      = 44100;            % Sampling rate
T       = 0.3;              % Duration
Spl1    = 75;               % SPL of input signal 1
Spl2    = 75;               % SPL of input signal 2
rho     = 0;                % normalized correlation of signals
tau     = 0;
ild     = 0;

% Generate signals:
t  = [0:1/fs:T];
n1 = scaletodbspl(randn(length(t),1),Spl1);
n2 = scaletodbspl(randn(length(t),1),Spl2);
x1 = n1*sqrt((1+rho)/2) + n2*sqrt((1-rho)/2);
x2 = n1*sqrt((1+rho)/2) - n2*sqrt((1-rho)/2);

% Run the model and plot it
[ei_map,fc] = breebaart2001([x1,x2], fs, tau, ild);
plotfilterbank(ei_map,1,fc,fs,'audtick','lin');
breebaart2001_1_1.png

References:

J. Breebaart, S. van de Par, and A. Kohlrausch. Binaural processing model based on contralateral inhibition. I. Model structure. J. Acoust. Soc. Am., 110:1074--1088, August 2001.