Definition of Occupational hearing loss:

Occupational hearing loss is damage to the inner ear from noise or vibrations due to certain types of jobs or 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 sound vibration) may cause vibration intense enough to damage the inner ear, especially if the sound continues for a long time.

• 90 dB -- a large truck 5 yards away (motorcycles, snowmobiles, and similar engines range from 85 - 90 dB)
• 100 dB -- some rock concerts
• 120 dB -- a jackhammer about 3 feet away
• 130 dB -- 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 carry a high risk for hearing loss, such as:

• Airline ground maintenance
• Construction
• Farming
• Jobs involving loud music or machinery

In the U.S., the maximum job noise exposure is regulated by law. Both the length of exposure and decibel level are considered. If the sound is at or greater than the maximum levels recommended, protective measures are required.