Occupational hearing loss

Definition

Occupational hearing loss is damage to the inner ear from noise or vibration as a result of certain occupations or forms of entertainment.

Causes, incidence, and risk factors

Occupational hearing loss is a form of acoustic trauma caused by exposure to vibration or sound. Sound is heard as the ear converts vibration from sound waves into impulses in the nerves of the ear.

Sounds above 90 decibels (dB, a measurement of the loudness or strength of vibration of a sound), particularly if the sound is prolonged, may cause such intense vibration that the inner ear is damaged.

• 90 dB is about the loudness of a large truck about 5 yards away. Motorcycles, snowmobiles, and similar engines range around 85 to 90 dB.
• 100 dB is reached by some rock concerts.
• 120 dB is a jackhammer from 3 feet away.
• 130 dB is a jet engine from 100 feet away.

A general rule of thumb is that if you need to shout to be heard, the sound is in the range that can damage hearing.

Some jobs, such as construction, airline ground maintenance, farming, and jobs involving loud music or machinery, carry high risk for hearing loss. In the U.S., the maximum job noise exposure is regulated by law. Both the length of exposure and the decibel level are considered. If the sound is at or greater than the maximum levels recommended, protective measures are required.

Symptoms

The main symptom is partial or complete hearing loss. The hearing loss may get worse over time.

Signs and tests

A physical examination will not usually show any specific changes. Tests that may be performed include:

• Audiology/audiometry may determine the extent of hearing loss.
• A head x-ray or CT scan of the head may be used to rule out other causes of hearing loss, including other forms of acoustic trauma.

Treatment

The hearing loss may not be correctable. Treatment is aimed at improving residual hearing and developing coping skills.

Surgical reconstruction of the eardrum and the bones of the middle ear may occasionally be attempted to correct the hearing loss.

Protect the ear from further damage. Use a hearing aid, if necessary, to improve communication. Develop skills such as the use of visual cues and lip-reading. Use other technology and skills as appropriate to the extent of hearing loss.

Expectations (prognosis)

Hearing loss is often permanent in the affected ear. The loss may be progressive if measures are not taken to prevent further damage.

Complications

Hearing loss may progress to total deafness.

Calling your health care provider

Call for an appointment with your health care provider if hearing loss occurs, gets worse, or if other new symptoms develop.

Prevention

Protect your ears when you are exposed to loud noises. Wear protective ear plugs or earmuffs to protect against damage from loud equipment. Be aware of risks connected with recreation such as shooting a gun, driving snowmobiles, or other similar activities. Do not listen to loud music for long periods of time.

Illustrations

Ear anatomy

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Hearing loss - occupational ; occupational hearing loss