Sound Conditioning Modulates Auditory Sensitivity

Abstract

Preconditioning is an active process found in many neuronal and nonneuronal systems that creates tolerance to subsequent detrimental forms of trauma or stress. Preconditioning is usually induced by low level, nondamaging stimuli that can result in long-term protective effects. Preconditioning has been shown to increase tolerance in many biological systems, including ischemia, light damage in the retina, and noise damage in the cochlea. The preconditioning event that increases tolerance in the inner ear is termed either sound conditioning or toughening. Evidence continues to accumulate demonstrating the importance of reducing the deleterious effects of noise trauma by sound conditioning. Sound conditioning is an active process induced by low level, nondamaging noise exposure that creates long-term protective effects to subsequent detrimental forms of noise trauma. This phenomenon is now shown to occur in a variety of mammals, including gerbils, chinchillas, guinea pigs, rabbits, rats, mice, and of most importance, human subjects. Different sound conditioning paradigms have been proven successful in preventing pathological changes to the auditory system. In the present overview these studies are reviewed and the possible biological mechanisms underlying this phenomenon are discussed.