Shazam-Like Dolphin System ID’s Their Whistles: Scientific American Podcast

6 Nov

See on Scoop.itComputational Music Analysis

Olivier Lartillot‘s insight:

I am glad to see such popularization of research related to “melodic” pattern identification that generalizes beyond the music context and beyond the human species, and also this interesting link to music identification technologies (like Shazam). Before discussing further on this, here is first of all what this Scientific American podcast explains in a simple way the computational attempt of mimicking dolphins’ melodic pattern identification abilities:

 

“Shazam-Like Dolphin System ID’s Their Whistles: A program uses an algorithm to identify dolphin whistles similar to that of the Shazam app, which identifies music from databases by changes in pitch over time.

Used to be, if you happened on a great tune on the radio, you might miss hearing what it was. Of course, now you can just Shazam it—let your smartphone listen, and a few seconds later, the song and performer pop up. Now scientists have developed a similar tool—for identifying dolphins.

Every dolphin has a unique whistle.  They use their signature whistles like names: to introduce themselves, or keep track of each other. Mothers, for example, call a stray offspring by whistling the calf’s ID.

To tease apart who’s saying what, researchers devised an algorithm based on the Parsons code, the software that mammals, I mean that fishes songs from music databases, by tracking changes in pitch over time.

They tested the program on 400 whistles from 20 dolphins. Once a database of dolphin sounds was created, the program identified subsequent dolphins by their sounds nearly as well as humans who eyeballed the whistles’ spectrograms.

Seems that in noisy waters, just small bits of key frequency change information may be enough to help Flipper find a friend.”

 

More precisely, the computer program generates a compact description of each dolphin whistle indicating how the pitch curve progressively ascends and descends. This enables to get a description that is characteristic of each dolphin, and to compare these whistle curves and see which curve belongs to which dolphin.

 

But to be more precise, Shazam does not use this kind of approach to identify music. It does not try to detect melodic lines in the music recorded by the user, but take a series of several-second snapshot of each song, such that each snapshot contains all the complex sound at that particular moment (with the polyphony of instruments). A compact description (a “fingerprint”) of each snapshot is produced, that indicate the most important spectral peaks (let’s say the more prominent pitch of the polyphony). This fingerprint is then compared with those of each songs in the music database. Finally the identified song in the database is the one whose series of fingerprints fits best with the series of fingerprints of the user’s music query. Here is a simple explanation of how Shazam works: http://laplacian.wordpress.com/2009/01/10/how-shazam-works/

 

Shazam does not model *how* humans identify music. The dolphin whistle comparison program does not model *how* dolphins identify each other. And Shazam and the dolphin whistle ID program do not use similar approaches. But on the other hand, we might assume that dolphins and humans abilities of identifying auditory patterns (in whistles, in music for humans) rely on same core cognitive processes?

See on www.scientificamerican.com

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