ACOUSTIC TRAUMA CAUSES REVERSIBLE STIFFNESS CHANGES IN AUDITORY SENSORY CELLS

A common cause of hearing impairment is exposure to loud noise. Recent research has demonstrated that the auditory mechanosensory cells are essential for normal hearing sensitivity and frequency selectivity. Ho wever, little is known about the effect of noise exposure on the mecha nical properties of the auditory sensory cells. Here we report a signi ficant reduction in the stiffness and cell length of the outer hair ce lls after impulse noise exposure, suggesting that mechanical changes a t the cellular level are involved in noise-induced hearing loss. There is a recovery of the cellular stiffness and cell length over a two-we ek period, indicating an activation of cellular repair mechanisms for restoring the auditory function following noise trauma. The reduced st iffness observed at the cellular level is likely to be the cause for t he downward shift of the characteristic frequency seen following acous tic trauma. The deterioration and the recovery of the mechanical prope rties of outer hair cells may form important underlying factors in all kinds of noise-induced hearing loss. (C) 1998 IBRO. Published by Else vier Science Ltd.