Finding the frequencies given in a wav file I have a wav file containing a series of chords, each containing 3 or 4 notes, played concurrently.

I need to find the frequencies of each note in each chord, and I can use matlab to do any computation.

Currently I think I need to find the spectrogram of the wav file and convert the frequencies from normailsed frequencies to normal frequencies (I know the sampling rate). Here is the spectrogram:



Is this a good approach to solving this problem?

I've already tried it, but the spectrogram isn't particularly informative. Is there an alternative method that I'm ignoring?
Polyphonic pitch estimation is still a difficult problem.  Search on the MIREX forum for current research papers.  Simplistic spectrum based approaches usually require component pitches with extremely simple timbres (nearly pure unmodulated sine waves, etc.) rarely found in real-life polyphonic music.  More typical polyphonic music can contain a dense set of overlapping overtones plus other transient noises.  More complicated timbres creating polyphonic chords may require a statistical pattern matching based approach (against a database of potential instrument sounds), and/or machine learning algorithms, in addition to any signal processing for spectrum and envelope information.