causes > long term exposure to environmental noise...

Populations of people living near airports or freeways are exposed to levels of noise typically in the 65 to 75 dbA range. If lifestyles include significant outdoor or open window conditons, these exposures over time can degrade hearing. The U.S. EPA and various states have set noise standards to protect people from these adverse health risks. The EPA has identified the level of 70 db(A) for 24 hour exposure as the level necessary to protect the public from hearing loss (EPA, 1974).

• Environmental noise-induced hearing loss is the most common form of sensorineural hearing deficit. It was earlier thought that hearing loss occurred in aging and the term presbycusis was coined to describe such effects; however, later research showed that tribal communities not exposed to significant environmental noise did not experience age related degradation of hearing.
• Exposure to high levels of noise (>70 dB(A) or more) for extended periods of time can cause a permanent, sensorineural hearing loss. (See also noise regulation and noise health effects.)
• Noise-Induced Hearing Loss (NIHL) typically begins at 4,000 Hz and spreads downward and upward.
• Earplugs or earmuffs can help to reduce the noise that reaches the ear.
• The louder the noise is, the shorter the safe amount of exposure is. Normally, the safe amount of exposure is reduced by a factor 2 for every additional 3 dB(A). For example, the safe daily exposure amount at 85 dB is 8 hours, while the safe exposure at 91 dB(A) is only 2 hours (National Institute for Occupational Safety and Health, 1998). Sometimes, a factor 2 per 5 dB(A) is used.
• Personal electronic audio devices, such as iPods (iPods often reaching 115 decibels or higher), can produce powerful enough sound to cause significant Noise-Induced Hearing Loss, even though lesser intensities of even 70 dB can also cause hearing loss.