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Old 16th August 2012, 10:55 PM   #26471
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SY

I'd love to see your Fourier representation of the previously mentioned single flute note!
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Old 16th August 2012, 11:00 PM   #26472
DF96 is offline DF96  England
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Quote:
Originally Posted by simon7000
When you subtract the level matched input from the output what is left is distortion.
Not if the difference is merely due to a tone control. Unless you are using your own private definition of distortion.

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Originally Posted by simon7000
I thought you had posted before that noise and music are periodic!
No, just that they can be rendered periodic by pushing the 'repeat play' button on the CD player. This guarantees that a Fourier series can be used, so we really are just dealing with frequency components. Nothing fundamental changes, of course, but it makes the situation simpler for those who are unfamiliar or uncomfortable with the Fourier transform.
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Old 16th August 2012, 11:01 PM   #26473
SY is offline SY  United States
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As long as the flute note is finite in duration, it's transformable exactly as I've stated.
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Old 16th August 2012, 11:16 PM   #26474
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As long as the flute note is finite in duration, it's transformable exactly as I've stated.
Can you show an example?

That would require continuously changing magnitude and phase coefficients for each term.
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Old 16th August 2012, 11:31 PM   #26475
jcx is offline jcx  United States
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Default sounding like a broken record

did you miss the part about the Fourier Transform being taken on a fixed length time series record?

maybe what you really want to discuss is the spectrogram? - requires delay, short record frames for the overlapping fft

Spectrogram - Wikipedia, the free encyclopedia


or are your anecdotes about dissing Fourier series representations of finite time series records for not somehow really being something like how to do a "real time" identification of frequency content - which at the the limit is a oxymoron - since with no "history" there is no meaningful concept of frequency, periodicity

Last edited by jcx; 16th August 2012 at 11:35 PM.
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Old 16th August 2012, 11:40 PM   #26476
SY is offline SY  United States
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Can you show an example?
I just did. f can be ANY function, a noise, a flute note, whatever, as long as it's of finite length. Drop in any sequence of magnitude versus time. Perhaps you can copy my posts exactly and have your anonymous friend explain it to you.
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Old 16th August 2012, 11:40 PM   #26477
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Originally Posted by jcx View Post
did you miss the part about the Fourier Transform being taken on a fixed length time series record?

maybe what you really want to discuss is the spectrogram? - requires delay, short record frames for the overlapping fft

Spectrogram - Wikipedia, the free encyclopedia


or are your anecdotes about dissing Fourier series representations of finite time series records for not somehow really being something like how to do a "real time" identification of frequency content - which at the the limit is a oxymoron - since with no "history" there is no meaningful concept of frequency, periodicity
The issue was Fourier series used in a specific case.


But to make things clear, given a Fourier transform of a 20 second piece of music, what would be the lowest frequency component?
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Old 16th August 2012, 11:43 PM   #26478
DF96 is offline DF96  England
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Lowest component depends on the music, but the spacing and every component would be a multiple of 0.05Hz.
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Old 16th August 2012, 11:53 PM   #26479
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Lowest component depends on the music, but the spacing and every component would be a multiple of 0.05Hz.
Wow we don't even agree on this.

Last edited by simon7000; 16th August 2012 at 11:57 PM. Reason: Misread quote
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Old 17th August 2012, 12:03 AM   #26480
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So if a drummer is hitting a slow beat is the lf the drums note or the beat?
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