Noise-Induced Hearing Loss

The entire ear is a very sensitive structure; one of the most sensitive parts of the ear is the inner ear, and especially the hair cells of the cochlea and the auditory nerve. When you are exposed to harmful levels of sound, these inner ear structures can be damaged, often permanently. Injury can occur if you are exposed for a very brief period of time to a very intense sound (these are called impulse sounds), such as an explosion, or if you are continuously exposed to harmful levels of sound over an extended period of time.

Impulse sounds may cause severe damage to the inner ear, leading to noise induced hearing loss that is immediate and permanent. Tinnitus may also occur with this type of hearing loss, though it may fade over time; many people, however, experience tinnitus throughout their life, either constantly or only on occasion. Tinnitus and hearing loss may affect only one or both ears.

Being exposed over long periods of time to loud noise may also lead to tinnitus and hearing loss, though the degree of both depends on the level of noise and the duration of exposure. Some hearing loss may only be temporary, called a temporary threshold shift, and may subside 16 to 48 hours following exposure. Individual susceptibility of noise induced hearing loss varies.

People with noise-induced hearing loss report hearing sounds in a muffled and distorted manner; these individuals have difficulty understanding speech. Sometimes hearing loss is gradual and an individual will not realize it is happening; even in these cases, though, the hearing loss can be verified with a hearing test.

Sounds over 80 decibels are usually considered very dangerous for inner ear structures. These include things like firearms and motorcycles. Exposure to dangerous levels of noise can occur anywhere and at any age. There are many legal briefs on occupational noise induced hearing loss stating that many workplaces expose their workers to levels of noise that are too high and don’t provide the right protection.

Riding go-carts can cause exposure as can playing with cap guns and model airplanes. Noise-induced hearing loss and earbuds, especially when the music is cranked up to high volumes, go hand in hand. At home, vacuum cleaners and lawn mowers can be harmful. Researchers have even verified noise-induced hearing loss in cows that are exposed to agricultural machinery.

Noise-induced hearing loss is completely preventable. Wearing hearing protection like ear plugs and ear muffs is the most effective preventive measure to protect against noise-induced hearing loss. Aid devices, like hearing aids, can be used to improve hearing loss that has already occurred.
Research is being done to investigate drug therapies for prevention and treatment of noise-induced hearing loss as well.