The sound of music? 1 in 5 teens suffer from hearing damage

Boston - Over the past 20 years, hearing loss in teenagers has risen from 15 to 20 percent. Personal stereo devices such as iPods are one culprit, but noise in the streets and at work are responsible as well.

A recent study by researchers in Boston has revealed the hearing loss, which is usually permanent, is on the rise. Comparing government survey data from period 1988 to 1994 with the period 2005 to 2006, the increase is five percent, meaning that the ears of at least 1 in 5 teenagers in the age group between 12 and 19 are damaged to some extent. According to the study, this translates into an increase impacting 6.5 million teenagers. The results of this study appeared in today's Journal of the American Medical Association, and many who interpret the new numbers are quick to point out that teens often use portable music players for extended periods of time at loud volumes. The claim, however, is supported by recent study of children in Australia, which found a 70 percent increased risk of hearing loss due to the use of personal stereo devices. Potential hearing impairment from noise-levels, which usually means damage to the inner ear rather than to the eardrum, is dependent on two variable: sound-volume (measured in decibel) and the lengths of time the ear is exposed to it. An article in The Hindu, discussing the recent vuvuzela use during the World Soccer Championship, explains it as follow:

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.

While the safest and recommended exposure to noise is between the ranges of -20 decibel (dB) and +25 dB, the environment many of us live in today is far from ideal, considering that the noise pollution from normal traffic in a big city measures around 85 dB. However, if one is exposed to that for merely a short time, it does not have to be damaging. Problems do begin to arise when someone is exposed to 85 or 90 dB more than 8 hours a day, or to 100 dB for 2 hours. The scale is logarithmic: as the noise level rises the permissible time of exposure is drastically shorter. For the ear to receive 115 dB, for example, more than 15 minutes a day will be damaging -- and everything above 140 dB is outright destructive, even for less than 5 minutes. The science is inconclusive, though. An article in Science Daily, for example, quotes a young woman who measures how loud kids crank up the volume on their iPods o similar players. She speaks of 99 dB as so dangerously loud that one shouldn't listen to this longer than 15 minutes. The woman, Genna Martin, usually warns kids who love to crank it up, saying: "If you listen to it this loud now, by the time you're forty you won't be able to hear it anymore." When the same article speaks about recommended levels, it also says, about MP3 players, that "listening at full volume is not recommended for more than 5 minutes per day.". Decibel data To round this up, here a few decibel readings for common and uncommon noises, mainly gleaned from the Health Sciences University website with a few additions found here and there. All numbers express decibel (dB) levels. Mosquito (20, library noise level (40), refrigerator (50), normal conversation (60), hair-dryer (60-95), freeway traffic (70), barking dog, alarm clock (75), subway (90-115), crying baby, car horn (110), thunder, ambulance (120), noisy squeeze toys (135), airplane takeoff (140), vuvuzela (144), shotgun (170), rocket launch (180)