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I am trying to use wavelet transform to represent song in frequency domain using discrete wavelet transform to made decomposition and made the frequency of the singer in place the the song using Matlab

The problem that the dwt and the decomposition mades represent it only in time domain.

How can I represent it in frequency if DWT doesn't represent It what would do?

Thank you

Nick
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Malik Gambour
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1 Answers1

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When we say "frequency transform" or talk about "representing frequency" we are usually talking about the Fourier Transform, implemented as the DFT, or discrete Fourier transform. Andre is correct in the comments below when he says that the DWT is also a type of frequency transform; however, wen we say "represent song in frequency domain" it usually means DFT, not DWT.

That being said, I don't recommend the DWT for music and sound analysis because the analysis bands are fixed at one-octave, which is simply too wide to do anything meaningful with. There are other techniques related to wavelets that are more effective for audio, but I don't gather from your question that you are using one of them.

In addition to the DFT, which is usually implemented as the FFT, or fast Fourier transform, you may also want to read about the STFT (short-time Fourier transform).

Bjorn Roche
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  • This is not correct, scale (or resolution) and frequency are reciprocal concepts of each other. The main difference is that the DWT is has a logarithmic frequency scaling (similar to constant Q transform) while the FFT is scaling linear in frequency. – André Bergner May 15 '13 at 20:51
  • This is true. I have rewritten my answer. – Bjorn Roche May 16 '13 at 01:51
  • thank you I know about fast Fourier transform but wavelet as I read It is time frequency representation for this it is the best for music representation my problem exactly is how to make it in matlab – Malik Gambour May 16 '13 at 07:18
  • Your question is not clear. Did you google it? I came up with this: http://www.mathworks.com/help/wavelet/ref/dwt.html – Bjorn Roche May 16 '13 at 13:37
  • Also, the wavelet transform is NOT best for music representation. – Bjorn Roche May 16 '13 at 13:38
  • I am in sudan can't enter this blog can you give me another one – Malik Gambour May 21 '13 at 17:25
  • http://www.google.com/url?sa=t&rct=j&q=the++music+representation+with+wavelet&source=web&cd=10&cad=rja&ved=0CHAQFjAJ&url=http%3A%2F%2Fdjj.ee.ntu.edu.tw%2FTutorial_Wavelet%2520for%2520Music%2520Signal%2520Analysis%2520_2.pdf&ei=3rCbUcH3DsWviALf64GADA&usg=AFQjCNFAIJIh2bOrG5hqvxa0DliB_Mt8Yg this paper say why wavelet is good for music representing music and my research based on wavelet frequency representing music – Malik Gambour May 21 '13 at 17:43
  • I don't have space here to explain why these techniques don't work well in practice, but mostly they fail because of insufficient frequency localization. Our ears are very sensitive to slight changes in frequency, which, even at low resolution, is preserved in the Fourier transform as phase information. There are much better techniques for all of those things. You might be interested in this book for example: http://www.amazon.com/DAFX-Digital-Udo-ouml-lzer/dp/0470665998/ref=dp_ob_title_bk – Bjorn Roche May 21 '13 at 22:15
  • wow this book is too useful you are the best but it over my time limit would you give me edition after 2008 thank you – Malik Gambour May 21 '13 at 23:37