There is an example at Analyzing WAV Files with Perl. In this example, I needed to track the frequency of a tone versus time. I used Audio::Wav, PDL, and PDL::FFT.

This code includes various algorithms to track the frequency of a tone. The example graphs are for the algorithm that worked best for my application.

I have written some other audio analysis modules, also, so please let me know if you would like more examples.

It should work perfectly the first time! - toma