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About Noise-Induced Hearing Loss

We experience sound in our environment every day, such as the sounds from television and radio, people conversing, and traffic. Normally, we hear these sounds at safe levels that do not affect our hearing.

However, when we are exposed to harmful noise - sounds that are too loud or loud sounds that last a long time - sensitive structures in our inner ear can be damaged, causing noise-induced hearing loss. These sensitive structures, called hair cells, are small sensory cells that convert sound energy into electrical signals that travel to the brain. Once damaged, our hair cells cannot grow back. Noise-induced hearing loss is irreversible, and there is no cure.
Noise-induced hearing loss can be caused by a one-time exposure to an intense impulse sound, such as an explosion, or by continuous exposure to loud sounds over an extended period of time, such as noise generated in a mine or factory, or those who shoot regularly.

Sound is measured in units called decibels. On the decibel scale, an increase of 10 means that a sound is 10 times more intense, or powerful. To your ears, it sounds twice as loud. The humming of a refrigerator is 45 decibels, normal conversation is approximately 60 decibels, and the noise from heavy city traffic can reach 85 decibels. A noisy factory can reach levels of up to xx decibels.

Sources of noise that can cause noise-induced hearing loss include wind noise on motorcycles, firearms, mines, factories and construction sites, which can emit sounds from 85 decibels up to 150 decibels. Long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the time period before noise-induced hearing loss  can occur. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss.

Exposure to harmful sounds causes damage to the hair cells as well as the auditory nerve. Impulse sound can result in immediate hearing loss that may be permanent. This kind of hearing loss may be accompanied by tinnitus - a ringing, buzzing, or roaring in the ears or head. Hearing loss and tinnitus may be experienced in one or both ears, and tinnitus may continue constantly or occasionally throughout a lifetime. The Ear Institute, with branches across the country, offers advice and hearing tests – click here for a branch near you. For more about tinnitus and Hearing Health micronutrients, click here.

Continuous exposure to loud noise can also damage the structure of hair cells, resulting in hearing loss and tinnitus, although the process occurs more gradually than for impulse noise.