Noise and Hearing Loss
Noise is difficult to define!
People who study acoustics define noise as complex sound waves
that are aperiodic, in other words, sound waves with irregular
vibrations and no definite pitch.
In engineering, noise is defined as a signal that interferes
with the detection of or quality of another signal.
The combined disciplines of psychology and acoustics
(psychoacoustics) study the response of humans to sound. They
define noise as unwanted sound.
Is music noise? Is the hum of tires on a highway noise? Is the
surround-sound movie theater noise? Is the philharmonic concert
noise? And what about the accompanying beat for aerobic exercises
at the health club? Sounds that are soothing for some are
irritating to others.
An expert on noise, K.D. Kryter (1996) in his text
, Handbook of Hearing and the Effects of Noise,
(New York Academic Press) defined noise as "acoustic signals
which can negatively affect the physiological or psychological
well-being of an individual."
Basically, noise is unwanted sound. It is a pollutant and a
hazard to human health and hearing. In fact, it has been
described as the most pervasive pollutant in America.
Noise in our environment affects physical heath. Noise also
has psychological and social implications and affects our well
being and quality of life.
Unfortunately, public awareness of the hazardous effects of
noise is low - especially noise considered to be
non-occupational. To this end, the fourth Wednesday in April has
been declared International Noise Awareness Day (INAD). As part
of International Noise Awareness Day, a "Quiet Diet" is
encouraged and is launched by observing 60 seconds of no noise
from 2:15 to 2:16 PM. The reduction, if not stopping of everyday
noises around us raises our awareness of the impact noise has on
health and hearing.
According to the National Institute on Deafness and Other
Communication Disorders (
NIDCD) more than 30 million Americans are exposed to hazardous sound
levels on a regular basis. Of the 28 million Americans who have
some degree of hearing loss, over one-third have been affected,
at least in part, by noise. Visit the
"Wise Ears" Web site
for more information on noise-induced hearing loss.
Damage to the Inner Ear
Your ear receives sound waves and sends them through a
delicately balanced system to the brain. Part of this remarkable
system, the cochlea, is a chamber in the inner ear filled with
fluid and lined with thousands of tiny hair cells. The hair cells
signal the auditory nerve to send electrical impulses to the
brain. The brain interprets these impulses as sound. When you are
exposed to loud or prolonged noise, the hair cells are damaged
and the transmission of sound is permanently altered.
Noise Levels
Both the amount of noise and the length of time you are
exposed to the noise determine its ability to damage your
hearing. Noise levels are measured in decibels (dB). The higher
the decibel level, the louder the noise. Sounds louder than 80
decibels are considered potentially hazardous. The noise chart
below gives an idea of average decibel levels for everyday sounds
around you.
Painful
150 dB = rock music peak
140 dB = firearms, air raid siren, jet engine
130 dB = jackhammer
120 dB = jet plane take-off, amplified rock music at 4-6
ft., car stereo, band practice
Extremely Loud
110 dB = rock music, model airplane
106 dB = timpani and bass drum rolls
100 dB = snowmobile, chain saw, pneumatic drill
90 dB = lawnmower, shop tools, truck traffic, subway
Very Loud
80 dB = alarm clock, busy street
70 dB = busy traffic, vacuum cleaner
60 dB = conversation, dishwasher
Moderate
50 dB = moderate rainfall
40 dB = quiet room
Faint
30 dB = whisper, quiet library
Warning Signs of Hazardous Noise
- You must raise your voice to be heard
- You can't hear someone two feet away from you
- Speech around you sounds muffled or dull after leaving a
noise area
- You have pain or ringing on your ears (tinnitus) after
exposure to noise.
Hazardous Noise
Sounds louder than 80 decibels are considered potentially
dangerous. Both the amount of noise and the length of time of
exposure determine the amount of damage. Hair cells of the inner
ear and the hearing nerve can be damaged by an intense brief
impulse, like an explosion, or by continuous and/or repeated
exposure to noise.
Examples of noise levels considered dangerous by experts are a
lawnmower, a rock concert, firearms, firecrackers, headset
listening systems, motorcycles, tractors, household appliances
(garbage disposals, blenders, food processors/choppers, etc.) and
noisy toys. All can deliver sound over 90 decibels and some up to
140 decibels.
Read more information on
noisy toys.
Can't my ears "adjust" and "get used"
to regular noise?
If you think you have "gotten used to" the noise you
are routinely exposed to, then most likely you have already
suffered damage and have acquired a permanent hearing loss.
Don't be fooled by thinking your ears are "tough"
or that you have the ability to "tune it out"! Noise
induced hearing loss is usually gradual and painless, but,
unfortunately, permanent. Once destroyed, the hearing nerve and
its sensory nerve cells do not regenerate!
An audiologist certified by the American
Speech-Language-Hearing Association (ASHA) can conduct a hearing
evaluation to determine if you do have a hearing loss. If you are
routinely exposed to noise, you should have your hearing checked
by an ASHA-certified audiologist on a regular basis, at least
once a year. In almost all states, a license to practice
audiology is also required.
Physical Changes
The most notable physical effect of noise exposure is loss of
hearing. Noise Induced Hearing Loss (NIHL) affects children,
adolescents, young adults, and older adults. The National
Institute on Deafness and Other Communication Disorders (NIDCD),
National Institutes of Health (NIH) the National Institute on
Environmental Health Sciences (NIEHS) and the National Institute
for Occupational Safety and Health (NIOSH) have noted that,
because of noise in our society, hearing loss is appearing much
earlier in life than would have been expected just 30 years
ago.
Noise not only affects hearing. It affects other parts of the
body and body systems. It is now known that noise:
- Increases blood pressure
- Has negative cardiovascular effects such as changing the
way the heart beats
- Increases breathing rate
- Disturbs digestion
- Can cause an upset stomach or ulcer
- Can negatively impact a developing fetus, perhaps
contributing to premature birth
- Makes it difficult to sleep, even after the noise
stops
- Intensifies the effects of factors like drugs, alcohol,
aging and carbon monoxide
Research is on-going and continues to provide data suggesting
the devastating effects of noise on health. Research is also
investigating factors that may contribute to one's
susceptibility to noise induced hearing loss.
Other Changes
Noise can also hamper performance of daily tasks, increase
fatigue, and cause irritability.
Noise can reduce efficiency in performing daily tasks by
reducing attention to tasks
.
This is a concern of employers when it comes to assuring
workers' safety. It is also a concern to a growing number of
educators interested in human learning.
Because of noise, we often find ourselves fatigued and
irritable. We don't even realize the effect until the noisy
hubbub stops and we feel relief.
From another perspective, your own inability to hear and
understand others clearly can cause you to feel angry and
frustrated
.
Instead of accepting the problem is yours, you misdirect your
feelings to others and blow up at them.
Noise also makes speech communication harder
.
More concentration and energy is needed not only to listen and
hear over the noise but also to speak louder above the noise. As
a result, voices can be strained and vocal cord abuses, such as
laryngitis, develop. It is a physical strain to carry on even an
enjoyable conversation in the presence of noise.
One demonstration of the effects of noise on behavior was done
by recording how passers-by responded to a person-in-need in the
presence of noise. While a noisy lawnmower was running, a woman
with a broken arm dropped some books and tried to pick them up.
No one stopped to help her. When the lawnmower was turned off and
the scene repeated, several people stopped to help her retrieve
the books.
Researchers have also looked at the effect of excessive noise
in school classrooms and have drawn conclusions that are
seemingly obvious, yet often minimized. In one study, test
results of students from a school near railroad tracks were
compared to results of students far away from the tracks.
Students in the quiet school performed better on the test.
Another study found that students whose classrooms face noisy
streets do not do as well in school as students in classrooms
facing away from noisy streets. Finally, another study
demonstrated that noise distracts both teachers and students.
There is no question that noise is both a public health hazard
and an environmental pollutant as well. Many of its effects are
well known and many of its effects continue to unfold through
research.
Protect Yourself from Noise
The key word in dealing with noise is prevention! We want to
eliminate unwanted noise when we can. When noise cannot be
eliminated, we want to keep it as low as possible. Here are some
things to do:
Wear hearing protectors
when exposed to any loud or potentially damaging noise at work,
in the community (heavy traffic, rock concerts, hunting, etc.)
or at home (mowing the lawn, snow blowing the driveway, etc.).
Cotton in your ears won't work. Hearing protectors include
ear muffs and ear plugs (not swimmer's plugs), some that
are custom-made and individually molded. This protection can be
purchased at drug stores, sporting goods stores or can be
custom-made. Check with your audiologist to find out what best
suits you.
Limit periods of exposure to noise.
Don't sit next to the speakers at concerts, discos, or
auditoriums. If you are at a rock concert, walk out for awhile
give your ears a break ! If you are a musician, wear ear
protection--it is a necessity! Take personal responsibility for
your hearing.
Pump down the volume!
When using stereo headsets or listening to amplified music in a
confined place like a car, turn down the volume. Remember: if a
friend can hear the music from your headset when standing three
feet away, the volume is definitely too high. Don't be
afraid to ask others to turn down the volume.
Educate yourself
about the damaging effects of noise and what you can do to
prevent your exposure to noise.
Educate others
and take action! Educate your children through discussion and
by example. Wear your ear protection and encourage your
children to follow your example. Provide them with ear
protection. Remind them to turn down stereo headsets. A rule of
thumb is that, if sound from a head set can be heard by others
3 feet away, it is too loud.
Be a responsible consumer.
Look for a noise rating when buying recreational equipment,
children's toys, household appliances, and power tools.
Choose quieter models, especially for equipment that you use
often or close to your ears like a hair dryer. If there is no
noise rating, contact the manufacturer and ask for one!
Inspect your child's toys
for noise danger just as you do for small parts that can cause
choking. Remember, too, that children tend to hold toys close
to their ear which can pose additional threat for hearing
damage.
Have your hearing tested
by an audiologist certified by the American
Speech-Language-Hearing Association (ASHA), especially if you
are concerned about possible hearing loss. Remember the warning
signs of over exposure to noise.
Be aware of the noise in your environment and take
control of it
when you can. Be an advocate for reducing noise pollution. Your
county may have a local noise ordinance. Find out what you can
do in your community to advocate for quiet. For example, some
schools have set a decibel limit for the music played at school
dances in order to protect the students' hearing.
Be an advocate!
Remember there are no regulations governing how loud sound can
be in public places such as discos, movie theaters, dance
clubs, exercise centers. Work with owners, managers, and
community leaders to create a healthier less noxious listening
environment.
Workplace Noise
Many people are exposed to hazardous noise levels at work,
including firefighters; military personnel; disc jockeys; subway
workers; construction workers; musicians; farm workers;
industrial arts teachers; highway workers; computer operators;
landscapers; factory workers; and cab, truck, and bus operators,
to name a few. And, they number nine million according to the
U.S. Environmental Protection Agency (EPA).
Continued exposure to more than 85 decibels (dBA) of noise may
cause gradual but permanent damage to hearing. Hearing loss is
accelerated by louder noises. Noise can also hamper job
performance, increase fatigue, and cause irritability.
Federal Occupational Safety and Health Administration (OSHA )
regulations require that, when engineering controls and/or
administrative controls cannot reduce noise levels in industry to
an eight-hour time-weighted average (TWA) level of less than 85
dBA, a hearing protection (or conservation) program must be
established. A successful hearing loss prevention program
benefits both the employee and the employer. Employees are spared
disabling hearing loss and may experience less fatigue and better
health in general. Employers benefit from reduced medical
expenses and worker compensation costs. Overall, there is
improved morale and work efficiency in the workplace.
OSHA requires a five phase hearing conservation program for
industry:
-
Noise Monitoring
Sound levels must be measured. Results are used to decide:
(a) which employees need to be in the hearing conservation
program, (b) whether hearing protection devices must be used
or be available on an optional basis, (c) which hearing
protection devices are appropriate for different noise levels
of the facility.
-
Audiometric (Hearing) Testing
All employees in a hearing conservation program must have
baseline and annual hearing tests.
Baseline audiometric testing helps the employer to
determine the presence or absence of a pre-existing hearing
loss and may assist the employer in determining job placement
for the employee.
Annual audiometric testing assesses the effectiveness of
the hearing conservation program. Each annual audiometric
test is compared with the emplpoyee's baseline test to
determine if there has been any deterioration in the
employee's hearing. There are no better alternatives than
quality audiometric testing to determine if workers are
protected from the damaging effects of noise.
-
Employee Training
Employees involved in a hearing conservation program must
receive annual education and training on (a) the effects of
noise on hearing, (b) hearing protection devices (their
availability to employees, their advantages and
disadvantages, techniques for proper selection, fit, use, and
care) and, (c) the purpose and procedures of audiometric
testing. By being involved in education, employees learn how
to protect their hearing when exposed to loud noise, both on
and off the job.
-
Hearing Protectors
Hearing protection devices should be made available to all
employees. Mandatory versus optional use is determined by
noise exposure monitoring. Hearing protection devices must be
worn by employees whose eight hour TWA is 90 dBA or greater
and by employees whose TWAs are between 85-90 dBA if they
display standard threshold shifts in hearing levels. A
standard threshold shift is defined by OSHA as "a change
in hearing threshold relative to the baseline audiogram of
10dB or more for the frequencies 2000, 3000, and 4000 Hz in
either ear." Hearing protection devices must meet sound
recution levels required by OSHA.
-
Recordkeeping
Sound measurement results, equipment calibration results, and
audiometric test records of employees must be maintained for
specific periods of time.
The skills of a knowledgeable professional are essential to
assure an effective and successful hearing conservation and
protection program. For the audiometric testing phase, OSHA
specifically requires supervision by an audiologist,
otolaryngologist, or physician. As a professional with
specialized training and expertise in all areas of hearing, the
audiologist is able to assist and guide industry for better
hearing health of employees.
Home, Community, and Recreational Noise
Exposure to damaging noise does not come only form the
workplace. If you use stereo headsets, operate power tools for
yard work, have a long daily commute in heavy traffic, or use a
number of household appliances, you still may be exposed to
potentially damaging noise.
Recreational activities such as hunting, target shooting,
motorboating, waterskiing, jetskiing, snowmobiling, motorcycle
riding, woodworking, rock music, or stereo headsets are sources
of hazardous noise. So are some movie theaters, home
entertainment centers, car stereo systems, health clubs, dance
clubs, bars, and amusement centers.
Just in our day-to-day living activities we can also be
exposed to damaging noise when we use lawnmowers, hairdryers,
blenders, power saws, weed-wackers, leaf blowers, food
choppers/processors, and other convenience appliances.
Children's toys can also be hazardous, e.g., toys with
horns and sirens, toy vacuum cleaners and vehicles, musical
instruments, talking dolls, squeeze toys, and battery-operated
toys that emit sounds.
Dealing with noise and its effects is a personal
responsibility, a work-place responsibility, and a community
responsibility. The first and obvious rule is avoid loud noise
whenever possible. A good rule of thumb is to remember that if
you must shout to be heard, then you should be avoiding the
situation or using ear protection.
Visit our news room for more information about the
dangers of environmental noise and hearing health.
Links