I do research in music information retrieval. See the ISMIR 2003 paper below. In short, it searches for landmarks in the spectrogram, hashes those landmarks, th

I do research in music information retrieval. See the ISMIR 2003 paper below. In short, it searches for landmarks in the spectrogram, hashes those landmarks, then compares those hashes against database hashes for temporal continuity. http://www.ee.columbia.edu/~dpwe/papers/Wang03-shazam.pdf http://www.ee.columbia.edu/~dpwe/papers/Wang03-shazam.pdf A seminal paper on audio fingerprinting is the one by Haitsma and Kalker. http://ismir2002.ismir.net/proceedings/02-fp04-2.pdf http://ismir2002.ismir.net/proceedings/02-fp04-2.pdf