Correlation between two audio files

Hi all,

I want to get the correlation as a probability of two audio files in .wav format. I already tried corr function in MATLAB as http://www.mathworks.com/matlabcentral/answers/132025-comparing-the-tone-of-musical-instruments-in-matlab says. Now I can get the correlation between same audio file (I copied the original file and get correlation) as 1. But when I use two audio files with different lengths, It gives an error like ??? Error using ==> corr at 102 X and Y must have the same number of rows. Now I want to know can't we use corr function to get correlation of two audio files with different length? And if can't how can I solve my problem. Please guide me.

Thanks in advance.