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10 Nov 2010.
We live in a noisy world. On the job, we are exposed to the sounds of office or industrial equipment and machinery. Off the job, our hearing is assaulted by noise from traffic, construction, loud music and jet airplanes. All of the loud sounds of our noisy world can contribute to hearing loss. In fact, noise has become a major cause of hearing loss.
How does loud noise cause damage?
Exposure to loud noise causes damage to the delicate hair cells in the inner ear that are responsible for conducting auditory signals to the brain. With each exposure, a few more cells are damaged and some may be destroyed. Once these cells are destroyed, they cannot be replaced. The cells responsible for conducting higher pitches of sound are usually the first to be destroyed
The damage occurs in two ways. Intense sound waves can blast away the vital hair cells of the inner ear. Intense sounds can also produce a stress reaction which, if it continues for more than a few minutes, can make the delicate hair cells more susceptible to damage from the noise.
Damage from noise can result from a simple, severe incident, such as an explosion. More commonly, noise-induced hearing loss is the result of repeated exposure to loud noise.
If people feel that loud noises don’t bother them any more, they are probably already suffering hearing loss!
How loud do noises have to be to cause damage?
The following table gives approximate decibel (dB) levels typical of various activities – circumstances can vary the decibel level. Noise is measured in decibels – over 85-90 decibels can produce hearing loss. Duration of noise exposure is also important.
| Sound level |
in decibels (dB)
| Common sounds |
An increase of ten decibels increased the impact of the sound ten-fold.
Sound at the 70dB level transmits 1,000 times as much energy as sound at 40dB.
|30 || Whisper, quiet library |
|40 || Quiet office |
|50 ||Rainfall, refrigerator |
|60 ||Dishwasher, normal conversation, sewing machine |
|70 ||Hair dryer, heavy traffic, telephone |
|80 ||Alarm clock, subway, vacuum cleaner |
|90 ||Electric razor, lawnmower, shop tools, truck traffic |
|100 ||Chain saw, stereo (above halfway) |
|110 ||Rock concert, power saw |
|120 ||Jet takeoff (from 22m), nightclub, close thunder |
|130 ||Jack hammer |
|140 ||Shotgun, fire alarm NB Approx pain threshold |
|160 ||Loudest rock band on record |
|180 ||Rocket launch (from 45 m) |
Rules of thumb to decide if the noise level is dangerous –
If you’re in a noisy environment and you have to significantly raise the level of your voice or shout to be heard
If the noise leaves the ears ringing or feeling ‘full’
If voices begin to sound dull or hollow – as if they are coming out of a barrel!
If the noise makes the ears hurt
In these cases the noise is loud enough that it risks hurting your ability to hear. It is enough to inflict permanent damage.
Who is most at risk?
Generally, the workers at greatest risk include fire fighters, police and military personnel, construction and factory workers, farmers, musicians and truck drivers.
Extended exposure to noise around the home can also put you at risk of hearing loss. Loud hair dryers, vacuums, dishwashers, lawn mowers and home repair tools such as drills, sanders and saws can take their daily toll on hearing.
Is everyone affected the same way?
Susceptibility to noise-induced hearing damage varies considerably. When two people have worked side by side with the same noise exposure – one might develop a severe hearing problem and the other might not.
The biological reasons for these differences are unknown but are currently being researched. Effects of various drugs on people’s susceptibility to noise exposure is also being researched.
The bottom line, though, is that approximately one-third of people with hearing impairment suffer from noise-induced loss.
Are young people at risk?
Yes! Although people have varying vulnerability to noise-induced hearing loss, people of any age can suffer from noise damage. Researchers at the University of Florida have found that approximately 17 % of students aged 10 to 20 years old tested already have lost some ability to hear.
And the problem will keep getting worse if they don’t protect themselves from the piercing decibels of loud music, motorcycles and other assaults on their ears.
President Clinton has recently had hearing aids fitted after having trouble over a long period of time with high frequency sounds.
One of his doctors pointed out that such a loss is very common and usually caused by ageing and early exposure to loud noises. He said, “High-frequency hearing loss is mostly due to noise exposure usually as a teenager listening to rock-‘n-roll or playing in bands", such as he did.
Can noise-induced hearing loss be prevented?
Yes! Everyone should understand the hazards of noise and practice good ‘hearing health’ in everyday life.
This includes –
Know which everyday noises can damage and at what level
Wear ear plugs or other protective devices (special earplugs and ear muffs are available for a variety of activities). Even simple muffs can give a protection of approx. 35 decibels
Be alert to hazardous noises in the environment
Protect children who are too young to protect themselves
Make family, friends and colleagues aware of noise hazards
Visit an audiologist as soon as you suspect a hearing loss
Know how to care for your ears when travelling, especially by air – see Better Hearing Australia’s brochure ‘Travel Tips’
What strategies need to be implemented?
Personal strategies -
Protecting the hearing of individuals starts with making sure they have the information they need.
Most people don’t realise how easily noise-induced hearing loss can happen. And also how much permanent damage can be done. They also don’t realise that when permanent damage is done, hearing aids will not restore normal hearing.
People need to know that both the level of the noise and its duration can influence the danger to hearing.
Parents and other care givers need to ensure strategies are in place to protect the hearing of individuals in their care.
Occupational strategies -
Hearing conservation programs in work places need to include
Sound surveys to access the degree of hazardous noise exposure
Controls to reduce exposure
Education to inform at-risk individuals why and how to prevent hearing loss
Hearing protection devices being available
Testing workers to detect hearing changes
Government regulations applying to noisy industries should be revised to include all industries and all employees. And programs need to be monitored to ensure effectiveness.
Research has shown that effective hearing conservation programs can result in reduced cost for workers’ compensation, enhanced worker morale, reduced absenteeism, fewer accidents and greater productivity.
Not to mention healthier and better hearing people at work!
General strategies -
Individuals can make a difference! Everyone can help by supporting the following strategies –
Consumer goods should be labelled with their noise emission levels
Manufacturers should be encouraged to design quieter industrial equipment and consumer goods
Planning authorities should promote requirements to control environmental noise
Media campaigns are needed to develop public awareness of the effects of noise on hearing and the devices available to protect hearing
Protection from noise-induced hearing loss should be stressed in schools and by other groups working with children and young people
Self-education materials for adults should be readily available
Community and government support should be increased for research into noise-induced hearing loss.
Can tinnitus also result from exposure to excess noise?
Tinnitus is an experience of sound like ringing, buzzing, roaring or other noise in one or both ears or ‘somewhere in the head’. It may be temporary, intermittent or permanent. For some people it may be slight while for others it can seem very loud.
And yes! Tinnitus can be an effect of excess noise.
Is there hope for better times for future generations?
Yes. As with other disabilities, research is seen as the way to develop new, more effective methods to prevent, diagnose, treat and eventually eliminate diseases and disorders, which result in hearing loss.
What are the directions for future research?
Some of the topics for future research include –
Better understanding of the internal workings of the ear
Potential drug therapies and other treatment strategies to reduce noise-induced hearing loss.
Noise measurement and control techniques
Better hearing protector designs
More accurate predicting of noise-induced hearing loss
Better labelling of potential danger by manufacturers
Evaluation of hearing conservation programs and optimum standards for industries
Genetic bases for vulnerability to noise-induced hearing loss
Better Hearing Australia, a member of the International Federation of the Hard of Hearing, is an enthusiastic supporter of research in these and other areas involving hearing loss.