There has been a fair amount of research in the Music Information Retrieval (MIR) community that borrows from image processing techniques for the likes of audio

There has been a fair amount of research in the Music Information Retrieval (MIR) community that borrows from image processing techniques for the likes of audio fingerprinting, onset detection, tempo estimation, chord recognition, etc. Most of the techniques used start by transforming the audio into some time-frequency representation (like an STFT, but also short-time versions of the wavelet transform, constant-q transform, etc) as is done here. For a specific implementation of computer-vision related techniques used for audio fingerprinting, see: http://ecee.colorado.edu/~fmeyer/class/ecen5322/waveprint.pdf http://ecee.colorado.edu/~fmeyer/class/ecen5322/waveprint.pd... However, a Google Scholar search should produce a lot more examples.