The Math Trick Behind MP3s, JPEGs, and Homer Simpson’s Face

This is also how the smartphone app Shazam can recognize a song. It splits the music into chunks, then uses Fourier’s trick to figure out the ingredient notes that make up each chunk. It then searches a database to see if this “fingerprint” of notes matches that of a song they have on file. Speech recognition uses the same Fourier-fingerprinting idea to compare the notes in your speech to that of a known list of words.