Sound: To MelSpectrogram...

A command that creates a MelSpectrogram object from every selected Sound object by band filtering in the frequency domain with a set of triangular filters.

The filter functions used are all triangular in shape on a mel frequency scale. Each filter function depends on three parameters, the lower frequency fl, the central frequency fc and the higher frequency fh. On a mel scale, the distances fc-fl and fh-fc are equal for each filter. The filter function is as follows:

H(f) = 0 for ffl and ffh
H(f) = (f - fl) / (fc - fl) for flffc
H(f) = (fh - f) / (fh - fc) for fcffh

In general the number of filter values stored in each frame of the MelSpectrogram is an order of magnitude smaller than the number of sound samples in the corresponding analysis frame.

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© djmw, October 22, 2014