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Protect Yourself from Noise-Induced Hearing Loss
Noise may not just be annoying; at high intensity it can be damaging. As a result, millions of Americans suffer from noiseinduced hearing loss, or NIHL. A single, very loud sound can cause NIHL, but most people get it from regular exposure to
sounds of 80 dB and above. Whether noise is encountered on the job or in the community, most people are at risk for NIHL if
they don’t take precautions.
Why Worry about Hearing Conservation?
Of the 28 million Americans who suffer from some degree of hearing loss, nearly one-third have been affected, at least in part, by
noise. Researchers have discovered that NIHL makes it difficult to experience and enjoy not only sound but silence as well.
Millions of Americans suffer from “ringing in the ears” known as tinnitus. People with tinnitus hear sounds that are only in their
own ears such as ringing, whistling, buzzing, or clicking, and these phantom sounds can become distressing. While there are
several causes of tinnitus, NIHL has been identified as one of the most common culprits.
Tinnitus is only one of the symptoms of NIHL. Other symptoms include a gradual decrease in sound or a growing distortion,
particularly of speech comprehension. Because it develops slowly, a person with NIHL may not be aware of the impairment at
first. He or she may even be unconsciously compensating for the loss by reading lips or turning up the radio or television
volume. Finally, unlike many injuries or illnesses, hearing loss may be permanent and irreversible.
There are two types of noise-induced hearing loss: a temporary threshold shift (temporary loss of hearing) and a permanent
threshold shift (a shift in the person’s ability to hear soft sounds). The hair cells in the inner ear can be bent down by low
amounts of noise, but if the noise is over a long duration or extremely loud, these hair cells can be broken off and destroyed.
Recent research has shown that even without permanent hearing loss, some bundle branches of the auditory nerve can be lost
forever. Therefore, even temporary threshold shifts can cause permanent damage to the ear’s nervous system.
Noise in the Workplace: A Pervasive Hazard
Over the last two decades, government agencies have consistently identified NIHL as one of the top concerns of workers. Some
occupational health and safety experts even call noise the most pervasive hazard in the workplace. Yet occupational hearing loss
is a particularly insidious hazard because it sneaks up on the worker. Because it doesn’t make the headlines like an industrial
accident, noise is a “stealth hazard” that attracts little attention from the public.
Why Is Hearing on the Job So Important?
Hearing is vital to many aspects of safety and performance. Besides communicating with one another, workers must be able to
hear announcements and pages over a public address system, as well as fire and other evacuation alarms or vehicle back-up
signals. Equipment operators rely on subtle changes in sound to gauge whether their equipment is running correctly. Many
equipment operators cite the need to “hear” their machines as a reason for not wearing hearing protection; they actually will be
able to hear the machines better with hearing protection than without, but will need time to adjust to the differences in their
perception. The lower frequency noise of a grinding machine transmits well through hearing protection, much like the lower
frequency of drums from music transmits well through a closed car. Good hearing helps workers avoid accidents and reduces the
likelihood of serious injury. Studies show that workers in high-noise environments typically lose more time from accidents and
are less productive than those exposed to lower noise levels. In addition, evidence shows that continuous high levels of noise
cause worker stress, fatigue, and post-work irritability. In some studies, noise has even been linked to increased blood pressure.
Hearing Conservation Programs - Protecting Workers from the Start
The first line of defense against occupational noise is to diminish loud sounds at their source, wherever possible. Such methods
are called engineering controls and involve measures such as installing “silencers” such as mufflers and baffles on equipment.
Acoustic barriers (such as specially constructed walls) can dampen sound from nearby machinery and are another excellent way
to guard hearing. If the equipment cannot incorporate a silencer or acoustic barrier, or other engineering controls prove
impractical, or if the worker cannot be moved away from the noise source entirely, the last line of defense to dampen noise is by
blocking the noise with hearing protection devices (HPDs), such as earplugs or earmuffs. In general, HPDs do not eliminate all
sound—which would be both impractical and potentially dangerous—but, if properly used, they reduce noise to safer levels.
Unfortunately, HPDs have one big drawback: no matter how effective the device, it only works if the wearer fits it correctly and
uses it when necessary. This is true of hearing conservation programs in general; they rely on the cooperation and motivation of
workers and management alike to make them effective.