Protecting against noise trauma by lateral efferent activation

Abstract

Protection against noise trauma is demonstrated by preconditioning guinea pigs to a low level, non‐damaging acoustic stimulus before exposure to noise that causes a temporary threshold shift. Sound conditioning results in a significant protection of the auditory brainstem response (ABR) threshold compared to the group exposed only to the acoustic trauma. The mechanisms underlying the phenomenon of sound conditioning are not yet known, but a role for the lateral efferent system is suggested. Experimental evidence demonstrates that sound conditioning causes an up‐regulation of dopamine and an increased release onto the afferent dendrites under the inner hair cells. The activation of the lateral efferent system by sound conditioning is believed to protect against excitotoxicity at the afferent dendrites beneath the inner hair cells, and thereby protect against acoustic overstimulation.