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 human subjects. Different sound-conditioning paradigms have been proven successful in preventing pathological changes to the auditory system. These studies are reviewed in the present chapter and the possible biological mechanisms underlying this phenomenon are discussed.