Dear Dan, and list,You are quite right. The level independence of the critical bandwidths (CB) over wide sound level ranges excludes an origin in the cochlea.
There are compelling data indicating that the origin is in the central nucleus of the inferior colliculus (ICC).
http://www.ncbi.nlm.nih.gov/pubmed/3975613 http://www.ncbi.nlm.nih.gov/pubmed/7677631 http://www.ncbi.nlm.nih.gov/pubmed/9237756 http://www.ncbi.nlm.nih.gov/pubmed/10190753 http://www.ncbi.nlm.nih.gov/pubmed/10867285 Enjoy, Martin --------------------------------------------------------------------- Martin Braun Neuroscience of Music S-671 95 Klässbol Sweden email: nombraun@xxxxxxxxx web site: http://www.neuroscience-of-music.se/index.htm----- Original Message ----- From: "Daniel Bowling" <danielliubowling@xxxxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx> Sent: Monday, June 14, 2010 3:46 AM Subject: Rationale for Critical Bands
Dear List,Has anyone considered why humans exhibit critical bands in psycho-acousticalexperiments (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 soundpressure levels (because more auditory nerve afferents over longer portionsof the cochlea are activated by higher SPLs, and fewer afferents withinrestricted areas of the cochlea are activated by lower SPLs), but this doesnot 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