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Using Computers for Sophisticated Music Analysis
Tom Avril writes "Need an accompaniment for your melody? Seeking a virtual dancer to try out your new choreography? Or perhaps you're making a new TV commercial, and you need a snippet of music that sounds something like Radiohead, but a bit more mellow. Increasingly, sophisticated software can help with these sorts of tasks. We got a look at the latest from the nascent field of Music Information Retrieval, after its conference in Philadelphia: 'A key part of the conference each year is the announcement of results from a sort of software shoot-out — a competition in which various universities pit their music-analysis algorithms against one another. Entrants from more than a dozen countries competed in 18 tasks, using their computers to "listen" to selections of music, then identify such things as the genre, mood, composer or title. The eventual goal: to help people search for music they might like by combing through millions of audio files in a database. ... In another task, the computer had to identify tunes that someone hummed. "The idea is, you go into the karaoke bar and start humming, and the computer retrieves your song," Downie said.'"
One of my senior projects for college used a very similar but more detailed schema in recognizing musical patterns.
In musical terms, a step is the amount of change from note-to-note. The Parson Code is limited in which it only indicates the direction of the pitch, and not the amount. I simply took account the actual half-steps used between each pitch. Like the Parson Code, it would ignore the rhythm, and easily account for identical melodies that are in different keys.
Minuet in G would look something like this:
-7 2 2 1 2 -7 0 9 -4 2 2 2 1 -12 0 5 2 -2 -1 -2 2 1 -1 -2 -2 -1 1 2 2 -4 4 -2
It was fairly easy for me to find an exact match using that encoding, or match to a certain %, since more information is provided than using the Parson Code method.
I feel that this is not far off from how the human brain recognizes melodies as most people do not have perfect pitch, but relative pitch in which we can recognize a certain melody by the difference in pitch changes even when the melody is using a different rhythm, or is in a different key than the original.