Hearing conservation: industrial aspects in California.

Impaired hearing is a serious problem. The number of persons with a significant hearing loss has been estimated to be approximately 10 per cent of the population. Hearing loss owing to exposure to noise is becoming an increasingly important disease. Although it has been recognized for more than a century, little if anything was done to prevent it until a few years ago. The initiation of hearing conservation for employees has been undertaken by many of the large companies, particularly in California. Hearing conservation includes preemployment and follow-up hearing tests, control of noise at the source and personal protection (ear plugs, ear muffs).Noise-induced hearing loss is directly related to noise-exposure. Noise must be measured in terms of volume, wave length and length of exposure. Exposure must be analyzed for daily distribution and total time. Although the noise-exposure problem is a serious one, cooperation of employee, employer and the legal and medical professions to initiate preventive programs can reduce it to a minimum.