Subject: Re: Place-based pitch From: "Richard H." <auditory(at)AUGMENTICS.COM> Date: Tue, 30 Mar 2004 11:06:28 +0100Hi, There are various sorts of diplacusis: "Diplacusis binauralis" - when binaural sounds seem to be different due to our cochlea being physically frequency "misaligned" with the respect to the other ... the brain can "fuse" a certain amount of misaligment ... but not over a semitone. The misalignmemnt can either be due to "manufacturing tolerances" or due to physical distortion from Menieres etc. The fusing process is mandatory because the 2 cochleas CAN grow slightly differently even in healthy people. "Diplacusis echotica" - when one sound is reheard after a time delay ... suspected to be due to either brain issues, or to a SAW (surface acoustic wave) echo in the TM (Tectorial Membrane) of the cochlea. Another form of diplacusis is when a monaural tone is split into TWO tones because of major nonlinearities in the cochlea. Hope that helps ... Richard ----- Original Message ----- From: "Al Bregman" <al.bregman(at)mcgill.ca> To: <AUDITORY(at)lists.mcgill.ca> Sent: Wednesday, March 24, 2004 10:26 PM Subject: Place-based pitch > Dear list, > > There is a phenomenon that suggests a contribution of place information to > pitch at all frequencies: the phenomenon of diplacusis, the hearing of > different pitches for the same sound at the two ears (when presented to only > one ear at a time). It is hard to imagine how a temporal mechanism could > produce such an effect, but if the two cochleas were slightly different > anatomically, one could see how this phenomenon could occur. The idea is > that place plays a secondary role at all frequencies, perhaps choosing > between temporal conclusions that are close to one another in probability > based on the temporal mechanism (e.g., octave differences), but can > influence the pitches to be slightly "off" when the two cochleas have > different topologies. > > Al > ----------------------------------------------------------- > Albert S. Bregman, Emeritus Professor > Dept. of Psychology, McGill University > 1205 Docteur Penfield Ave. > Montreal, QC Canada H3A 1B1 > > Office Tel: (514) 398-6103, Fax -4896 > E-mail: al.bregman(at)mcgill.ca > ----------------------------------------------------------- --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.631 / Virus Database: 404 - Release Date: 17/03/04