IHC vs OHC hearing loss Sensorineural hearing loss

a normal neural tuning curve characterised broadly tuned low frequency ‘tail’, finely tuned middle frequency ‘tip’. however, there partial or complete damage ohcs, unharmed ihcs, resulting tuning curve show elimination of sensitivity @ quiet sounds. i.e. neural tuning curve sensitive (at ‘tip’) (see figure 5).

where both ohcs , ihcs damaged, resulting neural tuning curve show elimination of sensitivity @ ‘tip . however, due ihc damage, whole tuning curve becomes raised, giving loss of sensitivity across frequencies (see figure 6). necessary first row of ohcs damaged elimination of finely tuned ‘tip’ occur. supports idea incidence of ohc damage , loss of sensitivity quiet sounds, occurs more ihc loss.

when ihcs or part of basilar membrane damaged or destroyed, no longer function transducers, result ‘dead region’. dead regions can defined in terms of characteristic frequencies of ihc, related specific place along basilar membrane dead region occurs. assuming there has been no shift in characteristic frequencies relating regions of basilar membrane, due damage of ohcs. occurs ihc damage. dead regions can defined anatomical place of non-functioning ihc (such “apical dead region”), or characteristic frequencies of ihc adjacent dead region.