- About Us
Clarifying effects of noise exposure | Letters
Once again I would like to attempt to clarify issues regarding the effects of noise exposure.
Exposure Time Guidelines
Accepted standards for recommended permissible exposure time for continuous time weighted average noise, according to National Institute for Occupational Safety and Health and Center for Disease Control, 2002. For every three dBAs over 85dBA, the permissible exposure time before possible damage can occur is cut in half.
According to NIOSH part of CDC a U.S. Federal Agency, the continuous dB permissible exposure times are as follows:
85dB — eight hours
88dB — four hours
91dB — two hours
94dB — one hour
97dB — 30 minutes
100dB — 15 minutes
103dB — 7.5 minutes
106dB — 3.75 minutes
109dB — 1.875 minutes
112dB — .9375 minutes
115dB — .46875 minutes
The above chart explains, quite clearly, how much noise plus length of time one can be exposed to noise before possible/probable damage to hearing will occur. The damage will occur at the higher frequencies first then affect the mid and low frequencies.
At the higher frequencies we hear the consonants of the English language and we perceive clarity, when the loss travels to the lower frequencies then loudness, how much one has to increase volume, is affected.
In other words, people with high frequency hearing loss state that others are‚ “mumbling,” Usually they even deny hearing loss because they hear, “perfectly fine,” without any increase in volume because the low frequencies have yet to be affected.
The noise maps that we have seen show levels anywhere from 30-75 (dB) which is a day/night average. Almost all citizens have no grasp of what day/night averaging means. It is a somewhat more complicated formula that the U.S. Navy uses to, supposedly, explain the amount of damaging noise level we may be exposed to. Unfortunately this is not the case since hearing loss and tinnitus does NOT occur as a day/night average but occurs in real time.
Day/night averaging, usually measured over a period of one year, is like saying that ones feet are in boiling water and the head is in the freezer that the “average” body temperature will then be 50 degrees.
Hearing loss and/or tinnitus is the most common disability among Navy personnel. The most compensated disability in the armed forces is for hearing loss and tinnitus. There are many steps being taken to reduce this trend since billions of our tax dollars are being spent on this injury.
For citizens to politicize hearing loss/tinnitus is a disservice to our veterans, military personnel and private citizens. Hearing loss is a health issue, public and private, and is recognized as a non-visible, isolating handicap.
We must recognize that the effects noise, no matter where it comes from, will affect all citizens no matter what race, religion, sex, location or political persuasion.