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Noise Pollution and Hearing Loss

Noise has become an eternal part of our daily life. Hooting cars, Loudspeakers, and Listening to music using headphones are very common. Do we realize that exposure to loud sound does have permanent damage to our hearing Capacity? Not all sounds we are exposed to can be considered noise pollution. The World Health Organization (WHO) mentions that noise above 65 decibels (dB) is noise pollution. Further, it can be said that noise level becomes harmful when it exceeds 75 decibels (dB) and is more painful above 120 DB. It is always advised noise levels be kept below 65 dB during the day. During the night restful sleep is impossible when ambient noise levels are in excess of 30 DB.

United Nations Environment Programme (UNEP) website does some staggering reports. The report identifies that out of the 13 most polluted cities in South Asia 5 of them belongs to India. Noise pollution affects the animal species ability to hear. Regular exposure for more than 8 hours a day can permanently damage hearing ability.

Hearing loss is decreases the ability to hear and understand. It happens when the nerves that connect the brain do not work properly. Sometimes, hearing loss can be temporary. This temporary can turn to permanent damage when the damage happens on a regular basis. Exposure to Loud noise is particularly harmful to the middle and inner
ear. The cochlea located in the inner ear contains millions of hair cells. Exposure to Loud noise can damage the hair cells and membranes in the cochlea. Loud noise exposure for a long time does overwork hair cells in the inner ear, ultimately these cells get damaged or die. The hearing loss continues to increase as the exposure continues

If we have gone to watch a music concert, IPL, Football match, DJ where we have listened to loud sounds for along period. A common sign is generally observed that post leaving that place the hearing tends to be a little dull and inaudible. It becomes difficult to hear whispers, it might seem muffled. People tend to complain of ringing in the ears. Normal hearing tends to return within a few hours to a few days. The hair cells are very similar to blades of grass, they bend more as the sound is louder. They again become straight after a recovery period.

It needs to be mentioned here that loud noise damages too many of the hair cells, there are high chances some of them will get permanently damaged or die. Continuous exposure to loud noises will over a long period of time destroy many hair cells. This effect will gradually reduce the ability to understand speech, especially in noisy places. Eventually, if the hearing loss continues it will be progressive in nature. It will be difficult to understand speech even in quieter places.

The damage of hair cells also damages the auditory nerve that carries information to our brain. Early damages are generally not indicated in the Hearing Test or Audiometry Test. It creates ‘hidden hearing loss’ it becomes difficult to understand speech in a noisy area. The effect of loud noise over time does have a futuristic aspect. Once the damage is permanently affected it is impossible to recover. Even if the exposure to loud sounds has stopped then also the hair cells which have died cannot be rework able.

Probably the information does make us aware of the ill effects of loud sound exposure. It will be always advisable to avoid loud sounds as much as possible. People who are exposed to loud sounds due to their work requirements should go for protective devices such as Ear Muffs and Earplugs as protection. Further, it will always advisable to go for Hearing Test once a year to know if there is any form of detrition. It should always remember protection always better than cure.

Audiologist and Speech Language Pathologist
Mrs. Arpita Niyogi