M. Ulfendahl et al., THE VIBRATION PATTERN OF THE HEARING ORGAN IN THE WALTZING GUINEA-PIGMEASURED USING LASER HETERODYNE INTERFEROMETRY, Neuroscience, 72(1), 1996, pp. 199-212
The mechanical tuning characteristics of the hearing organ were measur
ed in response to sound stimulation using laser heterodyne interferome
try in in vitro preparations of temporal bones from waltzing guinea-pi
gs expressing different degrees of hearing organ and sensory cell dege
neration. Measurements were made at various stages of structural chang
es allowing us to correlate structure and mechanical function. It was
found that the characteristic frequency of the response at a given loc
ation in the cochlea occurred at lower frequencies than what is normal
ly seen and that the sharpness of the mechanical tuning was considerab
ly reduced when sensory hair cells were absent and the hearing organ s
tructurally altered. However, even when extensive hair cell degenerati
on was evident a residual mechanical tuning was present. These results
further support the concept that the sensory hair cells play a key ro
le in determining normal auditory tuning characteristics. It is sugges
ted that the basilar membrane mechanics gives rise to a broadly tuned
mechanical response on which a sharper tuning mechanism, originating f
rom the hair cells, is superimposed.