Objective   To investigate the protect ion of sound conditioning on acoustic trauma.

  Methods   Forty healthy guinea pigs with normal Preyers reflex were used.The animals were randomly divided into four groups:normal group, conditioning noise group, high-level noise group and conditioning noise followed by high-level noise group.Sound conditioning experimental model of animals was established.Auditory brainstem response(ABR)threshold was tested with audito ry electrical physiology method.Hair cell loss was measured by surface preparation technique.

  Results   Conditioning noise exposure protected hearing loss by 13 dB froman acoustic trauma that resulted in the following high-level noise exposure.Cochlear surface preparations indicated that the loss of hair cells induced by noise exposure was obvious.A significant difference was observed between high-level noise group and conditioning noise followed by high-level noise group at the first and the second turn of the basilar membrane.

  Conclusion   Sound conditioning experimental model of animals is established successfully with appropriate noise conditions.Mor phological changes in hair cell stem from noise exposure includes hair cell loss and other impairments instead of hair cell death.Sound conditioning can decrease hair cell loss induced by the follow ing high-level noise exposure.