[PD] Real-time frequency filtering and analysis

[Jaime Oliver]

you could also check sigmund~ it will give you a list of frequencies
and amplitudes in order of amplitude.

J

>
> I think this just reinforces what everyone is saying
> about the errors. Either you make it into a crazy
> competition to vote by banging your note the loudest
> and the mostest, or you accept a margin of error.
> As Jamie says the intensity and frequencies are all
> going to vary and interact.
>
> attached patch intented to investigate that, it makes
> little clusters of 10 votes (idealised sinewave "xylophone")
> separated in time by a value between 0 and 100ms at
> one of 3 frequencies chosen at random.
> What you wont get in reality is the notes being exactly
> the same frequency, there should be a fair degree
> of variance. When I used a focused noise source to
> approximate the xylophones inharmonic spectrum
> I couldn't see any correlation above chance. YMMV,
> especially if you tweak the windows/blocks .
>
> I got better initial results with the filter bank approach
> I think.
>
>
>
>
>
> On Wed, 28 Mar 2007 09:16:23 -0500
> "Charles Henry" <czhenry at gmail.com> wrote:
>
> > filtering in general may not be the best approach because some of your
> > partials from one xylophone note will overlap with other note's
> > partials.  They are inharmonic complex tones, which are not so easy to
> > predict.... you'll probably have to measure the frequencies of each
> > note of your xylophone to know exactly what the spectrum is like.
> >
> > In terms of averaging like Jamie suggested... suppose you want to
> > compute the expectation of the power spectral density.  You would take
> > the fft of the auto-covariance of your recieved signal, divided by the
> > number of blocks in your time frame.  (dividing by a number of blocks
> > will not in general be necessary, when all you need to do is find a
> > peak, with pique~ as before)
> > This will give you a very clear/accurate peak, without much
> > jitter/noise to clean up.
> >
> > Chuck
> >
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