Vuvuzela, the ancient South African horn, has found its way into FIFA and the headlines this soccer season. Although many soccer fans seem to see it as a way of egging their teams on, most people are unaware of its impact on their hearing mechanism!
Vuvuzela, the wind instrument invented by Neil Von Schalkwyk, creates a droning sound measuring 144dB, which is way above the normal recommended hearing range of -20 dB and +25 dB. When noise is too loud, it begins to kill nerve's endings in the inner ear. As the exposure time to loud noise increases, more and more nerve endings are destroyed. As the number of nerve endings decreases the hearing ability also dips. There is no way to restore life to dead nerve endings; the damage is permanent.
Habitual exposure to noise above 85 dB will cause a gradual hearing loss in a significant number of individuals and louder noises will accelerate this damage. For unprotected ears, the allowed exposure time decreases by one half for each five dB increase in average noise level. For instance, exposure is limited to 8 hours at 90 dB, 4 hours at 95 dB, and 2 hours at 100 dB. The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes/day. Any noise above 140 dB is not permitted.
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People differ in their sensitivity to noise. As a general rule, noise may damage hearing if a person has to shout over background noise to be heard. Repeated noise from the vuvuzela could hurt the ears since it can make the ears ring or make the person slightly deaf for several hours after exposure to the noise. Much to the chagrin of the players, broadcasters, spectators and television viewers alike, the FIFA refused to ban the Vuvuzela.
A ringing in the ears called tinnitus commonly occurs after noise exposure, and it often becomes permanent. Some people react to loud noise with anxiety and irritability; it may trigger an increase in the pulse rate and blood pressure or may even result in acidity. Very loud noise can reduce efficiency in performing difficult tasks by diverting attention from the job.
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Intensity of sound is measured in decibels (dB). The scale runs from the faintest sound the human ear can detect, which is labeled 0dB, to over 180dB, the noise at a rocket pad during launch. Decibels are measured logarithmically. This means that as decibel intensity increases by units of 10, each increase is 10 times the lower figure. Thus, 20 decibels is 10 times the intensity of 10 decibels, and 30 decibels is 100 times as intense as 10 decibels.
Prof. Dr Ravi Ramalingam is a Chennai-based ENT specialist and surgeon. Website:>www.kkrenthospital.org