The industrial and technological boom may have taken us all to higher levels of achievement, but these developments have also made the world a noisy place to live in.  Noise pollution is a growing health hazard and can be found almost everywhere.

Car alarms, television, radios, gaming arcades, household appliances, gunshots, discotheques, long usage of mobile phones and traffic congestion fill our cities with decibels (the measure of sound intensity).

Normally, we hear these sounds at safe levels that do not affect our hearing. However, when we are exposed to harmful noise—sound that are too loud or loud sounds that last a long time—sensitive structures in our inner ear can be damaged, causing noise-induced hearing loss (NIHL). The sensitive structures, called hair cells, are small sensory cells in the inner ear that convert sound energy into electrical signals that travel to the brain. Once damaged, our hair cells cannot grow back.

Unpleasant or unwanted sounds are not the only harmful noises to which we may be exposed. For example, the music at a concert and the construction sounds on the street can be equally damaging to the inner ear. Loud sounds (acoustic energies) delivered with equal intensity or over extended periods of time, regardless of their source, are equally dangerous.

Eventually, continued or repeated exposures to high intensity sound can cause acoustic trauma to the ear. This trauma can result in hearing loss, ringing in the ears (tinnitus), and occasional dizziness (vertigo), as well as non-auditory effects, such as increases in heart rate and blood pressure.

The following is a list of occupations that are most susceptible to hearing loss which may lead to Occupational noise induced hearing loss.

• Agriculture
• Mining
• Construction
• Manufacturing
• Utilities
• Transportation
• Military
• Musicians
• Orchestra conductors

WHO IS AFFECTED BY NIHL?

People of all ages, including children, teens, young adults, and older people, can develop NIHL.

WHAT SOUNDS CAUSE NIHL?

The loudness of sound is measured in units called decibels. For example, the humming of a refrigerator is 40 decibels, normal conversation is approximately 60 decibels, and city traffic noise can be 85 decibels. Sources of noise that can cause NIHL include motorcycles, firecrackers, and small firearms, all emitting sounds from 120 to 150 decibels. Long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the time period before NIHL can occur. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss.

Although being aware of decibel levels is an important factor in protecting one’s hearing, distance from the source of the sound and duration of exposure to the sound are equally important. A good rule of thumb is to avoid noises that are “too loud” and “too close” or that last “too long.”

CAN NIHL BE PREVENTED?

NIHL is 100 percent preventable. All individuals should understand the hazards of noise and how to practice good hearing health in everyday life. To protect your hearing, remember these three words: Walk, Block and Turn:

• Walk away from loud sounds.
• Block noise by wearing earplugs or other hearing protective devices when involved in a loud activity (special earplugs and earmuffs are available at hardware and sporting goods stores).
• Turn the sound down on stereos and mp3 devices. Listening to an mp3 device at maximum volume (usually around 105 decibels) for more than 15 minutes per day may cause a permanent hearing loss.
• Know which noises can cause damage (those at or above 85 decibels.)
• Be alert to hazardous noise in the environment.
• Protect the ears of children who are too young to protect their own.
• Make family, friends, and colleagues aware of the hazards of noise.
• If you suspect hearing loss, have a medical examination by an otolaryngologist (a physician who specializes in diseases of the ears, nose, throat, head, and neck) and a hearing test by an audiologist (a health professional trained to measure and help individuals deal with hearing loss).
• Never be, or allow children to be, near firing guns or close to exploding fireworks.
  • If it is necessary for you to fire a gun, then good quality heavy duty ear-muffs must be used. If you fire a gun regularly, then ear-plugs should be used underneath the ear-muffs.
• Well fitting ear-muffs should be worn during the use of any power tools, loud machinery or vehicle that makes talking difficult, especially if unprotected use has ever caused ringing in the ears or a sensation of dulled hearing.
• Protective cabins should be used on tractors.
• If a safety helmet or sun hat should be worn during the noisy activity (eg. mowing the lawn), then good quality foam-rubber ear-plugs should be used, inserted carefully in the ears according to instructions.
• Headphones can be safely used to listen to music without disturbing others, so long as the volume is not too high. It is the volume, and to a lesser extent how long you listen, not the headphones themselves, that causes the damage. If other people can hear the music from your headphones, it is too loud.
• For young adults it may be nightclubs that are the major source of damaging levels of noise. It is better to avoid nightclubs, but if you do wish to attend a nightclub or if you are under pressure to do so:
  • agree to go only occasionally, less often than once a week
  • stay at the club no longer than necessary
  • spend most of the time there away from the dance-floor in a situation where it is possible to hold a conversation
  • And do not combine a visit to a club with first visiting a pub with amplified music.

*RESEARCH CONDUCTED IN INDIA ON NOISE INDUCED HEARING LOSS AND OCCUPATION INDUCED HEARING LOSS:

A study conducted in India showed that the major industries responsible for excessive noise and exposing workers to hazardous levels of noise are textile, printing, saw mills, mining, etc. Hearing protectors should be used when engineering controls and work practices are not feasible for reducing noise exposure to safe levels. Earmuffs, ear plugs and ear canal caps are the main types of hearing protectors.

In India, NIHL has been a compensable disease since 1948. It is only in 1996 that the first case got compensation. Awareness should be created among workers about the harmful effects of noise on hearing and other body systems by implementing compulsory education and training programs. World Health Organization estimated 360 million individuals in the world with disabling hearing loss, out of which 91% are adults, and only 9% are children. Prevalence of disabling hearing impairment in South East Asia is 2.4% in children; 9.5% in adults below 65 years and up to 48% in adults above the age of 65.  The most common etiological factor for this age-related deafness is noise pollution.

National Institute on Deafness and Other Communication Disorders estimates that 15% of the population has got decreased hearing due to loud noise that may be noise at work, leisure activity or use of mobile phone only.

Two publications in Indian Journal of Otology state that use of mobile phone may lead to sensorineural deafness and if continuously for more than 30 min, may lead to 10 dB transient hearing loss.

Thus, it becomes extremely important to not ignore the impending hazardous aftermaths of noise and take appropriate precautions to safeguard your hearing!

COMPILED BY-SABEEHA ABBASSI
CHILD SMITH
(LISTENING EARS-BANGALURU)

REFERENCES:
(ONLINE)

• medicine.net.com
• hearinghealthfoundation.org
• www.ncbi.nlm.nih.gov
• en.wikipedia.org/wiki/Noise-induced_hearing_loss
• www.cyh.com
• indianjotol.org