yule walker Psd of .Wav file

hi i m new to matlab.i m trying to obtain 4th order yule walker psd estimate of a wav file ,using pyulear command but it is generating error message every time.

[b1, f] = wavread('bcopy.wav');

>> [Pxx fs] = pyulear(b1,4)

??? Error using ==> aryule at 29

X must be a vector with length greater or equal to the model order.

Error in ==> arspectra at 75 [a,v] = feval(method,x,p);

Error in ==> pyulear at 65 [Pxx,freq,msg,units,Sxx,options] = arspectra(method,x,p,varargin{:});

plss help me with this.

Answer 1

[Wayne King]

You want to just input one column vector and not the matrix

b1 = b1(:,1);
[Pxx fs] = pyulear(b1,4);

[777]

well i got the result but i did'nt understand it.

[Wayne King]

because your audio file was 2-channel but pyulear only works on vectors, it was interpreting the column dimension of your matrix as the vector length and complaining that it was only 2 while you were asking for a model of length 4

Answer 2

[Wayne King]

What is the length of b1? is it only three samples in length? or empty?

You have the model order of 4 but apparently your input b1 is less in length than that.

[777]

while using waveread i have not specified anything about sample size .does the error here mean default sample size is less than 4.???workspace shows the value of b1 as <71680x2 double>