Noise Induced Hearing Loss and Its Prevention (cont.)
James K. Bredenkamp, MD, FACS
Dr. Bredenkamp recieved his medical degree from the University of California, San Francisco School of Medicine. He then went on to serve a six year residency at the University of California, Los Angeles School of Medicine in the department of Surgery.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
In this Article
- What is the importance of noise-induced hearing loss?
- What are acoustic trauma and noise-induced hearing loss?
- How can a person tell if a noisy situation is dangerous to their hearing?
- How loud can a sound get before it affects hearing?
- Do the duration and closeness of exposure to loud noise relate to hearing damage?
- What factors increase a person's susceptibility to noise-induced hearing loss?
- How else can noise affect a person?
- What are the regulations regarding on-the-job exposure to noise?
- How effective are hearing protection devices?
- What are the common problems with hearing protectors?
- Do hearing protectors prevent a person from communicating with others?
- How is hearing loss identified?
- What can be done to treat hearing loss?
- Find a local Ear, Nose, & Throat Doctor in your town
How else can noise affect a person?
After exposure to noise, tinnitus, which is a ringing or another sound in the ears, occurs commonly. The tinnitus is a sign that inner ear damage or nerve destruction has occurred. Initially the tinnitus is temporary, lasting only several hours. As more cumulative exposure and damage occur, the tinnitus will last longer until it eventually becomes permanent. Loud noise will also cause some people to have anxiety and irritability, an increase in heart rate and blood pressure, or an increase in stomach acid. In addition, very loud noise can reduce efficiency in performing difficult tasks by diverting attention from the job.
What are the regulations regarding on-the-job exposure to noise?
Habitual exposure to noise above 85dB will cause a gradual hearing loss in a significant number of individuals. Moreover, noise greater than 85dB will accelerate this damage. Accordingly, the U.S. Occupational Safety and Health Administration (OSHA) has imposed regulations nationwide regarding on-the-job exposure to noise. For unprotected ears, the allowed exposure time decreases by one-half for each 5 dB increase in the average noise level. For instance, exposure is limited to 8 hours at 90 dB, 4 hr at 95 dB, and 2 hr at 100 dB. The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes per day. Any noise above 140 dB is not permitted.
OSHA, in its Hearing Conservation Amendment of 1983, required the institution of a hearing conservation program in noisy workplaces. Such a program must include a yearly hearing test for workers exposed to an average of 85 dB or more of noise during their 8-hour workday. It turns out that approximately 25% of the American industrial workforce is exposed to this level of noise.
Ideally, noisy machinery and work places should be designed to be quieter, and/or the workers' time in the noise should be reduced. The cost of reducing noise exposure in these ways, however, is often prohibitive. As an alternative, individual hearing protectors are required when noise averages more than 90 dB during an 8-hour day.
When noise measurements indicate that hearing protectors are needed, the employer must offer at least one type of earplug and one type of earmuff without cost to employees. If the yearly hearing test reveals a hearing loss of 10 dB or more in the higher sound frequencies (pitch) in either ear, the worker must be informed. (The higher frequencies of sound are the most sensitive to noise damage.) Also, the worker must wear hearing protectors when noise averages more then 85 dB for an 8-hour day. Greater losses of hearing or the possibility of ear disease necessitates referral to an ear doctor (otolaryngologist).
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