The “active process” is a term used to describe amplification and filtering processes
that are essential for obtaining the exquisite sensitivity of hearing organs. Understanding
the components of the active process is important both for our understanding of the
normal physiology of hearing and because perturbations of the cochlear amplifier may
lead to such maladies as threshold shifts (both temporary and permanent), tinnitus,
sensorineural hearing loss and presbicusis. To date the cochlear amplifier has largely
been attributed to outer hair cell electro motility; however, recent evidence suggests,
that active properties of the hair bundle may also be important. Most likely both
somatic motility and active hair bundle movements contribute to establishing the cochlear
active process. This paper reviews recent evidence regarding known active processes
in the hair bundle gating compliance, and fast and slow adaptation.
Key Words
Active process - adaptation - gating compliance - hair bundle - met channels
