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Re: Rationale for Critical Bands

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


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.