The format is a sampled data format. The wav file format is just a binary file listing of samples with some format information at the start of the wav file (bits per sample, channels, etc.).
The WAVREAD function processes the wav file and returns some of the information (such as bits per sample and sample rate), along with all of the samples. For more information try the following at the MATLAB command prompt:
doc wavread
%or
help wavread
Here is an example that should help clarify this information. Listen to it to verify:
% stereo demonstration of wavread/wavwrite
clear all;
close all;
% wav sample parameters and time array
fs = 44100
Ts = 1/fs
nbits = 16
t=0:Ts:0.5;
% row vectors of samples
left = 0.99 * sin( 2 * pi * 2000 * t );
right = 0.99 * sin( 2 * pi * 200 * t );
% showing you the size
sizeLeft = size(left)
% flip to col vectors and concatenate
total = [ left' right' ];
% showing you the size
sizeTotal = size( total )
% plot it so we can see it
figure;
subplot(2,1,1);
plot( t, left );
title( 'left ear' );
subplot(2,1,2);
plot( t, right );
title( 'right ear' );
% write it out
wavwrite( total, fs, nbits, '2000HzInLeftEar200HzInRightEar.wav' );
% clear all variables so we can see what is reloaded
clear all;
disp( 'have written file and cleared all variables' )
% read it back in
[ y, fs, nbits ] = wavread( '2000HzInLeftEar200HzInRightEar.wav' );
% let's take a look at some data
sizeY = size(y)
fs
nbits
% setup time array
Ts = 1/fs
t=0:Ts:0.5;
left = y(:,1)';
right = y(:,2)';
% plot it so we can see it
figure;
subplot(2,1,1);
plot( t, left );
title( 'left ear' );
subplot(2,1,2);
plot( t, right );
title( 'right ear' );
