Re: Cepstrum computation (Paul Boersma )

Subject: Re: Cepstrum computation
From:    Paul Boersma  <boersma(at)FON.HUM.UVA.NL>
Date:    Wed, 23 Jun 1999 03:15:01 +0200

Laszlo Toth wrote: > if(||FFT(x)||==0) { y=-BigNumber} > else {y=log(||FFT(x)||) > > Where "BigNumber" is some big constant. This is not correct, since you would like to preserve monotonicity, i.e. the relation that smaller ||FFT(x)|| means smaller y (or at least not larger y). So it would have to be: if (||FFT(x)|| <= exp(-BigNumber)) { y=-BigNumber} else {y=log(||FFT(x)||) But note that adding a small number makes the function differentiable: y = log (||FFT(x)|| + epsilon) Bill Hartmann wrote: > You can always add a little broadband noise to keep the power spectrum > finite at all frequencies. The "epsilon" trick is equivalent to adding white noise. Perhaps we should instead add a noise whose spectrum is equivalent to the zero-phon curve? Paul Boersma Institute of Phonetic Sciences, University of Amsterdam Herengracht 338, 1016CG Amsterdam, The Netherlands

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