Subject: Re: Rationale for Critical Bands From: "Richard F. Lyon" <DickLyon@xxxxxxxx> Date: Mon, 14 Jun 2010 08:42:07 -0700 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>The "critical bandwidth" is a simplification of the concept of a psychophysical "auditory filter", which is a bandpass filter that can be measured with various experiments, such as detection of probe tones in notch-noise maskers. These measurements can be done at different levels, and show a clear level-dependence of the psychophysical auditory filter and its bandwidth, or critical band, following a pattern consistent with the variation seen in cochlear mechanics. Some types of experiments reveal a level dependence in the CB, presumably based directly on the cochlear filtering. Other experiments show a more level-independent CB, and that's what corresponds to the further processing in IC, according to some experimenters. Find more in books: http://www.google.com/search?q=%22critical+band%22+%22level+dependence%22&tbs=bks:1 Dick At 9:46 AM +0800 6/14/10, Daniel Bowling wrote: >Dear List, > >Has anyone considered why humans exhibit critical bands in >psycho-acoustical experiments (e.g. masking, loudness summation, >detectability of phase changes)? Is the assumption that the origin >of critical bands is in the physiology of the cochlea? If so, how is >this justified? If critical bands result from overlap/interference >of vibrations on the basilar membrane one would expect their >bandwidths to change significantly at different sound pressure >levels (because more auditory nerve afferents over longer portions >of the cochlea are activated by higher SPLs, and fewer afferents >within restricted areas of the cochlea are activated by lower SPLs), >but this does not seem to be the case. > >In vision, attempts to rationalize psychophysical phenomena in terms >of retinal physiology have had very limited success. > >Any thoughts would be much appreciated. > >Thanks, > >Dan