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Noise and Hearing Facts

posted Sep 10, 2011, 9:46 AM by David Sitter
Noise Threatens Hearing

Noise is one of the leading causes of hearing loss in the 28 million people with impaired hearing in the United States, and health statistics suggest a trend that the incidence of hearing loss is occurring at younger and younger ages.  Noise-induced hearing loss, though preventable, is permanent.

How Loud is Too Loud?

To know if a sound is loud enough to cause damage to your ears, it is important to know both the level of intensity and the length of exposure to the sound. The unit used to measure environmental sound intensity is the decibel (dBA). Zero decibels is approximately the softest sound the healthy human ear can hear. The scale increases logarithmically; that is, the level of perceived loudness doubles every 10 decibels. Experts agree that continued exposure to noise above 85 dBA, over time, will eventually harm hearing. In general, the louder the sound, the less time required before hearing will be affected.

Noise-Induced Hearing Loss - How the Damage Occurs 

Loud noise assaults the delicate hair cells of the inner ear. Noise-induced hearing loss typically occurs gradually and without pain. After exposure to loud noise, a person may experience ringing in the ears or difficulty hearing. This is called a "temporary threshold shift". After a few hours (or in some cases, a few days), this temporary shift in hearing returns to normal. With repeated exposure, however, this temporary shift in hearing can become permanent. Once permanent hearing damage has occurred, it is not possible to restore hearing.

Pay Attention to the Warning Signs

Noise-induced hearing loss is cumulative across the life span. Often, by the time a person realizes that there is hearing loss, it is too late. But there are certain early warning signs to suggest that there may be a problem. If you experience any of the following early warning signs, have your hearing tested by a licensed audiologist, or have your ears examined by an ear doctor.

A ringing or buzzing (tinnitus) in the ears immediately after exposure to noise.
A slight muffling of sounds after exposure making it difficult to understand people when you leave a noisy area.
Difficulty understanding speech; that is, you can hear all the words, but you can't understand all of them.

Protect Your Hearing

To avoid noise-induced hearing loss, pay attention to the noises around you and turn down the volume whenever possible. Avoid or limit time spent in noisy sports events, rock concerts and night clubs. Wear adequate hearing protection, such as foam ear plugs or ear muffs, when you must be in a noisy environment or when using loud equipment.

Common Environmental Noise Levels Fact Sheet

How Loud is Too Loud? Experts agree that continued exposure to noise above 85 dBA over time, will cause hearing loss. To know if a sound is loud enough to damage your ears, it is important to know both the loudness level (measured in decibels, dBA) and the length of exposure to the sound. In general, the louder the noise, the less time required before hearing loss will occur. According to the National Institute for Occupational Safety and Health (1998), the maximum exposure time at 85 dBA is 8 hours. At 110 dBA, the maximum exposure time is one minute and 29 seconds. If you must be exposed to noise, it is recommended that you limit the exposure time and/or wear hearing protection.

Measure Up and Turn it Down: Decibel Levels Around Us The following are decibel levels of common noise sources around us. These are typical levels, however, actual noise levels may vary depending on the particular item. Remember noise levels above 85 dBA will harm hearing over time. Noise levels above 140dBA can cause damage to hearing after just one exposure.

Points of Reference, measured in dBA or decibels

- 0 The softest sound a person can hear with normal hearing
- 10 normal breathing
- 20 whispering at 5 feet
- 30 soft whisper
- 50 rainfall
- 60 normal conversation
- 70 vacuum cleaner at 3 feet
- 85 Hheavy truck at 50 feet
- 95 jackhammer at 50 feet
- 110 discoteque
- 120 thunder
- 125 Jet takeoff at 300 feet
- 140 threshold of pain