Re: can anyone help with this one... ("James W. Beauchamp" )


Subject: Re: can anyone help with this one...
From:    "James W. Beauchamp"  <jwbeauch@xxxxxxxx>
Date:    Tue, 6 Sep 2011 12:40:11 -0500
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

Brittany, Probably what is happening is that in the "transposed" speech, the amplitudes of the components are the same, but their frequencies have been shifted by a fixed multiplier. A four semitone upward shift would require a frequency multiplier of 2^(4/12) = 1.26. This will result in the natural formant resonances being shifted up, changing the quality of the voice considerably, such that an adult male voice can sound more like an adult female or child voice. This problem could be fixed using software that keeps the spectral envelope of the sound close to that of the original. If the program models speech in terms of an glottal excitation, which changes its frequency, and a vocal tract modulation, which is invariant with respect to the original, that may be what you want. The method of Homomorphic Speech Modelling does something like this. A talk on it is given at: http://www.ece.ucsb.edu/Faculty/Rabiner/ece259/digital%20speech%20processing%20course/lectures_new/Lecture%2012_fall_2010.pdf Pretty mathematical though. The question is Is there software out there that will do this? I actually think that the free download program Praat might do it because it inherently models signals in terms of excitation and filter. Maybe someone on this list knows of alternative software products. Jim You wrote: >From: Brittany Guidone <brittanyguidone@xxxxxxxx> >Date: Tue, 6 Sep 2011 08:17:59 -0700 >To: AUDITORY@xxxxxxxx >Subject: [AUDITORY] can anyone help with this one... > >Dear List,I am designing a study in which I planned to "morph" female > voices into male voicesand vice versa. The method I tried was simply to > change the pitch (using GarageBand,although I also tried Audacity). At >first I tried small transpositions, just 3-4 semitones up or down. > Our task is to identify individual speakers. The problem is that >the speakers were easily discernible before the transformation, however, >after the transposition, none of our pilot subjects were able to >differentiate between the various speakers. Can anyone help me >understand what is going on? What is known about the acoustic information >people use identifying individual speakers? Can anyone suggest a better >transformation? Thanks in advance,Brittany >From: Brittany Guidone <brittanyguidone@xxxxxxxx> >Date: Tue, 6 Sep 2011 15:56:06 +0000 >To: AUDITORY@xxxxxxxx >Subject: [AUDITORY] > >Dear List, > >To explain more about my original question: > >I mainly want to know if "morphing" or "changing" the pitch of a male >voice by p ositive 4 semi tones will change the components of the >original male voice (befo re it was morphed) in a way that will make the >two voices have different compone nts or "make up" in comparison to one >another, besides the fact that they will h ave different pitches. > >In other words, when the pitch of a voice is changed in audacity or >garage band then what other components of the voice are changed (besides >the pitch shift)? > >-Brittany >Sent from my Verizon Wireless BlackBerry


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