Hearing with selective inner hair cell loss.

In a comparative model study, the effect of selective inner hair cell loss on hearing threshold was investigated. Functional testing was related to a detailed morphological evaluation. Inner ears of homozygous Bronx waltzer mice (bv/bv) were investigated using light microscopy with Nomarski interference contrast optics and transmission electron microscopy. Hearing thresholds were determined using click evoked auditory brainstem responses at different ages. The histological evaluation was performed immediately after determination of the hearing threshold. The functional and histological findings were compared to the normal controls of the same age. Scattered loss of up to 70% of inner hair cells was found to cause only moderate elevation of hearing threshold.