[Effect of sound conditioning on click auditory brainstem response threshold shifts in guinea pigs]

ABSTRACT

Sound conditioning is exposure to a non-traumatic, moderate level of sound which increases inner ear resistance against further severe noise. In this study, we aimed to survey the effect of sound conditioning on auditory brainstem response [ABR] threshold shifts using click stimulus, and the effect of the frequency of conditioning on hearing protection. Fifteen guinea pigs were randomly divided into 3 groups. Two conditioned groups were exposed to 1 kHz, and 4 kHz octave band noise at 85 dB SPL, 6 hours per day for 5 days, respectively. On the sixth day, the animals were exposed to 4 kHz octave band noise at 105 dB SPL, for 4 hours. The control group was exposed to intense noise, 4 kHz at 105 Db SPL for 4 hours [without conditioning]. After exposure, ABR thresholds using click were recorded an hour, and 7 days after noise exposure. The results of the ABR with click stimulus showed less thresold shifts in conditioned groups than control [p 0.05]. Electrophysiological data of our study showed that sound conditioning has a protective effect against subsequent intensive noise exposure, and the frequency of conditioning does not have significant effect on ABR threshold shifts when using click stimulus