[music-dsp] measuring partial frequencies

jeffrey traer bernstein jeffyb at ccrma.stanford.edu
Tue Jan 13 11:23:00 EST 2004


Take an FFT of a window after the transients have died out and zero pad 
by a factor of 5 and then use parabolic interpolation on dB magnitude. 
You'll have to choose your analysis window judiciously as well. If it is 
a single piano note then the partials are far enough apart that the main 
lobe width is not as important as getting good sidelobe rejection.

That should be plenty accurate, you can take it as far as you want and 
zero pad or take as a big window as you want.

Zero crossing will not do.

Peter Thom wrote:

>Yeah, I'm looking for frequencies other than the fundamental.
>FFT isn't accurate enough, I want to measure frequencies within 0.01Hz.
>Would a bandpass filter and zero crossing counting do, or is that not
>accurate enough? How about autocorrelation?
>BTW, the tone is a piano tone, so it should be a relatively periodic
>tone.
>Any help is greatly appreciated.
>
>Peter
>
>
>-----Original Message-----
>From: music-dsp-admin at shoko.calarts.edu
>[mailto:music-dsp-admin at shoko.calarts.edu] On Behalf Of Joerg Spix
>Sent: Monday, January 12, 2004 5:47 PM
>To: music-dsp at shoko.calarts.edu
>Subject: Re: [music-dsp] measuring partial frequencies
>
>
>Hi folks,
>
>  
>
>>Peter Thom wrote:
>>    
>>
>>>What would be the best way to measure exact partial frequencies of a 
>>>tone? Any ideas?
>>>      
>>>
>>Do you mean the harmonics other than the fundamental?  If
>>so, SpectraLab (a PC application) performs that measurement
>>in an overall sense and gives a plot of the FFT for
>>isolating them.
>>    
>>
>
>I don't think he means (exact) harmonics but partial tones (sinoidal
>components of a musical tone with not neccesarily exact whole number
>multiples of the base freqency).
>
>Years ago I know "Lemur" did sinoidal tracking on a Macintosh. I think
>this beast still exists... If you don't have a Mac, still have a look at
>the manual so you might get some ideas what the program should do you
>are looking for.
>
>Joerg
>
>----
>Joerg.Spix (at) informatik.uni-oldenburg.de
>
>
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>  
>




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