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>From tothl Wed Jun 23 16:29:32 +0200 1999 remote from inf.u-szeged.hu
Date: Wed, 23 Jun 1999 16:29:32 +0200 (MET DST)
From: Toth Laszlo <tothl@inf.u-szeged.hu>
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To: auditory@lists.mcgill.ca
Subject: Re: Cepstrum computation
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On Wed, 23 Jun 1999, Paul Boersma wrote:

> I use the Praat fft, and don't get into trouble, since it is scaled so that
> its output is expressed in true spectral density, i.e. Pascal/Hertz.
>
This Praat fft must be magic. I give you a series of numbers, don't tell
anything about how its amplitude/sampling rate is related to the real world,
and it gives back values in Pascal/Hertz??
By the way, something I never understood: Let's suppose I have an auditory
model (software) and nice articles about how the model behaves for speech
signals at a given SPL. I have a PC with a soundcard. My software gets a
series of samples as input. No SPL's, just a series of integers. One turn
on the mike-preamp's knob, and the amplitude of the samples is different. One
move in the soundcard's mixer program, and the amplitude of the samples is
different. One multiplication with a constant, and the amplitude of the
samples is different. So, even if my talker talks at a nice 70dB SPL
normal conversational level, as he's supposed, is there any way I can
relate the absolute power of the signal to the amplitude of my samples?
I'm afraid not.

               Laszlo Toth
        Hungarian Academy of Sciences         *  "In our life there's if
  Research Group on Artificial Intelligence   *   In our beliefs there's lie
     e-mail: tothl@inf.u-szeged.hu            *   In our business there's sin
     http://www.inf.u-szeged.hu/~tothl        *   In our bodies there's die"