Download Noise Induced Hearing Loss

Noise
Induced
Hearing
Loss
When noise hurts!
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Noise induced hearing loss (NIHL) is irreversible hearing damage resulting from exposure to
high levels of noise. NIHL affects an estimated 10 to 15 million people in the USA, making
excessive noise exposure the most common cause of hearing loss.
The audiogram below shows hearing loss patterns for white males at ages 20, 30, 40, 50 & 60
years with 0, 10, 20, 30, and 40 years of noise exposure. NIHL develops gradually, and limits
our ability to hear higher frequency sounds. If NIHL spreads to frequencies where human
speech occurs (500-3000 Hz) , understanding speech will be difficult.
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What causes NIHL? Exposure to traumatic noise will cause permanent damage to the sensitive
hair cells of the inner ear and possibly the hearing nerve. The figure, below, shows the path of
sound from the ear (A) to the cochlea (A, B), where hair cells first amplify and then relay sound
via the auditory nerve to the auditory cortex of the brain.
From Dr. Li’s published research, C shows healthy hair cells, but D shows noise-induced
damage, indicated by fused hair cells (yellow arrows) and scars (white arrows). The damaged
hair cells (D) were subjected to traumatic noise exposure at 120 dB for just 5 min!
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NIHL is related to both noise intensity and the duration of exposure. The Table (below) shows
that louder sounds require shorter exposures before damage occurs. Why? Because a 10 dB
increase in sound level causes a 10 fold increase in sound intensity.
This means that the sound of an MP3 player set at a volume of 115 dB is about 1000 times
more intense than a vacuum cleaner sound volume of 85 dB, and a Rock concert can produce
sounds (120 dB) that are 100 times more intense than a lawnmower (100 dB)!
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The earbud generation loves their music, but too many love their music too loud, and that
presents a threat to their long-term hearing. Why? Because MP3 players and earbuds can
reach extremely high levels of sound with almost no distortion.
Personal Music Player (PMP) volumes generally range from 80-115 dB, but some players can
achieve a maximum volume of 120 dB. The hazard to hearing from listening to music at such
levels is extremely high, since levels exceeding 80 dB are considered risky.
Who is at risk? Though the data is incomplete, there is evidence that 5-10% of the earbud
generation are at risk for developing permanent hearing loss and chronic tinnitus after 5 years
of listening abuse. Even though only 5-10% of the total listeners are at serious risk, that still
adds up to 10s of millions world-wide!
Is there a safe volume? Studies indicate that there is very little threat of hearing loss at
listening levels below 80 dB, so this can be regarded as a safe listening level for PMPs for any
length of time.
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NIHL is preventable. How? Be mindful of sound levels that can cause damage (those above 85
dB), your proximity to the noise, and the length of time you are exposed. Be especially wary if:
 you have to raise your voice in normal conversation.
 the noise hurts your ears.
 you develop a continuous or temporary ringing in your ears.
 normal hearing isn’t restored until several hours after you get away from a noise source.
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Poorly treated hearing loss can be as damaging as untreated hearing loss. That is why
credentials matter! Education, training, and professional certifications often
determine the effectiveness of treatment.
Dr. Li-Korotky has AuD, PhD, and MD credentials, and she is Board certified in Audiology. The
doctor is a highly respected research scientist and clinical expert with more than 100
publications, including published research in noise-induced hearing loss.
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Wonderful doctor! Dr. Li is by far the most caring doctor I've ever seen. I had an unusual case
and she was determined to help me, even researching my medications and supplements to
see if they were part of my problem. I have one hearing aid and she continues to monitor my
hearing....love her! S.Z.
I have had three appointments and all three visits were beyond expectations. I am severely
hearing impaired and Dr. Li made sure I understood all the options open to me. The staff has
been very helpful as well and I was treated like a person instead of just a number. That is so
rare these days. I would highly recommend this company for all your audiology needs. R.H.
It's my pleasure to recommend Dr. Li, Ryan and the entire staff! I'm very happy with my
hearing aids and the staff support through the whole process from beginning to end has
been excellent! They are very committed to caring about their patients. R.S.
I had not had an audiology exam in many years. The exam performed by PNW Audiology
exceeded my expectations. The exam process and explanation of results were clear,
straightforward and reasonable. I would not hesitate to recommend PNW Audiology to
anyone having hearing concerns. J.K.