Subject:Re: cepstrum: computing epsilonFrom:Paul Boersma <boersma(at)FON.HUM.UVA.NL>Date:Wed, 23 Jun 1999 21:42:27 -0600On Jun 23, 7:46pm, Laszlo Toth wrote: > FFT (or, rather, DFT) is a formula that > converts a series of numbers into another series of numbers. For me. > (...) Now I see that by > "Praat fft" you meant "the spectrum analysis facilities (and the belonging > objects) in the Praat software package". Exactly. That is the advantage of having a program that models the physics (like Praat) instead of the mathematics (like Matlab). Someone complained about the problem of choosing the "epsilon" in a Matlab implementation of the cepstrum. In a Praat script, you can express this epsilon in physical units. So if you want to add white noise with a density of 10^-8 Pascal/Hertz, your cepstrum routine would be To Spectrum Formula... if row=1 ... then log10 (self[1,col]^2 + self[2,col]^2 + (1e-8)^2) ... else 0 fi To Sound (row one is the real part, row two the imaginary part; Matlab does have the advantage of doing complex arithmetic less verbosely) -- Paul Boersma Institute of Phonetic Sciences, University of Amsterdam Herengracht 338, 1016CG Amsterdam, The Netherlands tel: +31-20-5252385 / 5252183 (fax: 5252197) http://www.fon.hum.uva.nl/paul/

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