Re: Pitch orientation-discriminating feature detectors? (Al Bregman )


Subject: Re: Pitch orientation-discriminating feature detectors?
From:    Al Bregman  <al.bregman(at)MCGILL.CA>
Date:    Tue, 24 Sep 2002 14:16:09 -0400

Dear Daniel, On what scale were the frequency excursions? If it was a log-frequency scale, as I suspect it was, it is possible that the difference would disappear or be reversed if you swept up and down on a linear scale. What is the justification for the scale that you actually did use for the excursions? Al ------------------------------------------------- Albert S. Bregman, Emeritus Professor Dept of Psychology, McGill University 1205 Docteur Penfield Avenue Montreal, QC, Canada H3A 1B1 Office: Phone: +1 (514) 398-6103 Fax: +1 (514) 398-4896 Home phone & Fax: +1 (514) 484-2592 Email: al.bregman(at)mcgill.ca ------------------------------------------------- ----- Original Message ----- From: "Daniel Pressnitzer" <Daniel.Pressnitzer(at)IRCAM.FR> To: <AUDITORY(at)LISTS.MCGILL.CA> Sent: 24-Sep-02 1:46 PM Subject: Re: Pitch orientation-discriminating feature detectors? > Dear Eliot, > > There is a perceptual asymmetry that is linked to the direction of > pitch movement. Frequency peaks (upward-then-downward frequency > modulation) are more salient and produce much lower difference limens > than frequency troughs (downward-then-upward FM). This has been > described in detail by Demany and colleagues in a series of studies > published in JASA (see refs below). > > We are in fact starting a project to record cortical activity > associated with FM peaks and troughs, using magnetoencephalography -- > together with Laurent Demany and Andre Rupp. What we see up to now is > that the source waveforms in response to FM peaks consistently display > longer N1 latencies and larger N1-P2 amplitudes, when compared to > responses to matched FM troughs. > > Such an asymmetry might have something to do with previous reports of > EEG recordings examining upward vs. downward frequency glides. For > instance, Ruhm (1971) showed that upward glides produce bigger and > later N1-P2 responses than downward glides. > > The next question is of course why would it be useful in the real > world to process differently upward vs. downward frequency > movements... > > > Cheers, > > Daniel > > --- > > (at)Article{demany94, > author = {Demany, L. and McAnally, K.}, > title = {The perception of frequency peaks and troughs in wide > frequency modulations}, > journal = {J. Acoust. Soc. Am.}, > year = 1994, > volume = 96, > pages = {706-715} > } > > (at)Article{demany95a, > author = {Demany, L. and Clément, S.}, > title = {The perception of frequency peaks and troughs in wide > frequency modulations. II. Effects of frequency register, stimulus > uncertainty and intensity}, > journal = {J. Acoust. Soc. Am.}, > year = 1995, > volume = 97, > pages = {2454-2459} > } > > [there are two other Demany and Clément papers in JASA, 1995 and 1997] > > (at)Article{ruhm71, > author = {Ruhm, H. B.}, > title = {Directional sensitivity and laterality of electroencephalic > responses evoked by acoustic sweep frequencies}, > journal = {J. Auditory Res.}, > year = 1971, > volume = 11, > pages = {9-16} > } >


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