(HealthDayNews) -- Noise-induced hearing loss can be caused by one-time exposure to a very loud sound, or by repeated exposure to loud sounds over an extended period, according to the National Institute on Deafness and Other Communication Disorders.

Sound is measured in units called decibels. Normal conversation is about 60 decibels, the humming of a refrigerator is 40 decibels, and city traffic noise measures about 80 decibels.

Exposure to harmful sounds causes damage to the nerves and sensitive hair cells of the inner ear. Sources of loud noises that can cause hearing loss include motorcycles, firecrackers and firearms, all emitting sounds from 120 to 140 decibels.



-- Anne Thompson

Last Updated: Sep-28-2004