Re: onset detection

[robert gjerdingen <r-gjerdingen@xxxxxxxxxxxxxxxx>]

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.

Andy,

	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