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Re: onset detection

On Dec 25, 2007, at 5:57 AM, Andrew McGuiness wrote:

First, the script looks for negative slope in the energy curve of the sound, with energy calculate by averaging 100 millisecond blocks, to eliminate very local fluctuations. If the sound file is recorded clean, with no spill, this works well to identify the general area of the onset.


For a counter example, you might look at an old paper of mine, “Smooth” Rhythms as Probes of Entrainment,” _Music Perception_ 10 (1993): 503-508 (<http://faculty-web.at.northwestern.edu/music/ gjerdingen/Papers/PubPapers/SmoothRhythms.pdf>). There the perceived onsets occur at positive-to-negative zero crossings of the second derivative of energy. This would be in a region of all positive slope, if I'm not misunderstanding your method.

Best wishes for the Holidays,
Bob Gjerdingen
Northwestern Univ. School of Music