physiological mechanism behind critical bands?

[Woojay Jeon <wjjeon@xxxxxxxxxxxxxx>]

Can anybody refer me to any sources that discuss the physiological mechanism
in the auditory system that gives rise to critical bands? Are critical bands
due purely to the spectral integration effect in the basilar membrane (which
is usually simulated by cochlear filterbanks), or is there more processing
done in higher processing levels (such as in the central auditory system)
that gives rise to the critical band effect? Exactly which parts of the
auditory system are responsible for critical bands and how?

Woojay Jeon.