A textbook case of noise-induced hearing loss walked into Dr Sanjay Sachdeva's ENT clinic at Max Super Speciality Hospital in Delhi a little over a year ago.
"It was a 12-year-old boy who had lost his hearing completely after watching the Indian Grand Prix without earmuffs," recalls Dr Sachdeva. The roar from collective car engines can take noise levels up to an ear-splitting 140 dB.
"He needed cochlear implants to restore hearing, but such cases are rare. Temporary threshold shifts in hearing [temporary hearing loss] after listening to loud sounds, however, are very common, especially among people under 30," says Dr Sachdeva.
That loud sounds cause impaired hearing is something we all know. What most of us don't know is that even listening to loud music for as little as an hour can cause irreversible hearing loss.
GETTING AN EARFUL
The popularity of earbuds, which now come free with smartphones and auditory devices, are compounding the problem.
"Most earbuds do not block outside sounds; this prompts users to turn up the volume. Also, because they fit inside the ear, they blast loud music directly into the ear canal, which causes more damage to the nerve endings in the inner ear than music being played out loud," says Dr Ajay Swaroop, chairman, ENT at Ganga Ram Hospital.
The risk of damage depends on the volume, duration and frequency of exposure, which puts musicians, recording engineers, factory workers, bars or night-club workers and earbud users at risk.
Exposure to sounds greater than 90 dB for an average of eight hours a day without hearing protection causes irreversible damage. Most young people listen to music at 110 dB to 120 dB, which is well over the safe level of 85 dB or below. At that level, loud noise can cause permanent hearing loss after just 75 minutes.
More than 5% of the world's population - 360 million people - have disabling hearing loss (328 million adults, 32 million children), estimates the World Health Organisation, with one in three people over 65 years being affected.
"Normally, people lose hearing by one decibel each year after the age of 55, but now audiograms - the result from an audiometry test - of 40-year-olds read like they belong to someone over 70," says Dr Swaroop. "Hearing damage in children growing up using earbuds will be far greater by the time they are 40 years old."
While there is no data for India, US data show that hearing loss has gone up by 33% among American teens since 1996, the Journal of the American Medical Association reported.
GETTING A FIX
"Most earbuds used are of poor quality. If you like music, it makes sense to ditch them and invest in noise-cancelling headphones that go over the ear and block outside noise," says Dr Sachdeva. If you are going to use earbuds, the American Auditory Society's rule of thumb is 60/60 - listen to no more than 60 minutes at a time, at 60% of the maximum volume on your device. "If you're wearing earbuds and other people can hear the music, it's too loud."
Temporary hearing loss is reversible. Apart from difficulty in hearing, ringing or "muffling" after exposure to loud sound is a sign that you need to give your ears at least 24 hours to recover.
"The body, especially when it's young, has great powers of regeneration, so it's never too late to stop abuse. Audiometry tests will record improvements in six months." says Dr Swaroop.