REDUCING NOISE DAMAGE BY USING A MID-FREQUENCY SOUND CONDITIONING STIMULUS

SOUND conditioning guinea pigs to a 6.3 kHz tone at 78 dB SPL for eith er 13 or 24 days provides significant physiological (auditory brain st em responses, ABR; and distortion product otoacoustic emissions, DPOAE ) and morphological (cochleograms) protection against a subsequent tra umatic exposure (6.3 kHz, 100 dB SPL for 24 h) delivered 2 h after sou nd conditioning. Threshold shifts (ABR, DPOAE) were significantly redu ced and the degree of hair cell loss was minimal. When a 1 week pause was given between the end of the sound conditioning and the traumatic exposure, protection was still observed, but to a lesser degree. These findings demonstrate that mid-frequency sound conditioning protects a gainst noise trauma and that the protective effect is maintained for a t least 1 week.