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>From tothl Wed Jun 23 19:46:39 +0200 1999 remote from inf.u-szeged.hu
Date: Wed, 23 Jun 1999 19:46:39 +0200 (MET DST)
From: Toth Laszlo <tothl@inf.u-szeged.hu>
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To: auditory@lists.mcgill.ca
Subject: Re: Pascal per Hertz
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On Wed, 23 Jun 1999, Paul Boersma wrote:

> Praat is not Matlab. The sound is in a Sound object, which has information
> about the time domain and about the sampling, and is considered to carry
> samples that represent air pressures in Pascal. The "fft" converts this
> Sound object into a Spectrum object

FFT is not Matlab. FFT is not Praat. FFT (or, rather, DFT) is a formula that
converts a series of numbers into another series of numbers. For me.
That's why I didn't get your previous mail. Sorry. No I see that by
"Praat fft" you meant "the spectrum analysis facilities (and the belonging
objects) in the Praat software package".
(At first I thought "Praat FFT" was something like "Bruun FFT" or
"Sorensen FFT"...)

> In Praat, the maximum absolute value of the samples is 1, which, if considered
> Pascals, corresponds to an intensity of 94 dB re auditory threshold.
> [...] you should use a dB meter once,
> with your computer set to a maximum input gain, and use the same gain
> setting for all subsequent recordings.
>
Sounds uncomfortable to give a dB meter with each copies of a speech
recognizer (well, usually you'll have to buy a special mike with it
anyway, so...). Or should we avoid non-linear preprocessing?


               Laszlo Toth                    *    "I don't like people
        Hungarian Academy of Sciences         *     working all day,
  Research Group on Artificial Intelligence   *     only working just to
     e-mail: tothl@inf.u-szeged.hu            *     see next tomorrow"
     http://www.inf.u-szeged.hu/~tothl        *                 /Accept/