Firdaus Khan
Rule of thumb: MP3 users should set the volume no higher than 60 percent of its full capacity when using "ear buds" style headphones, like those that come with iPods. With over–the–ear headphones, one can use 70 percent as the maximum as per a report in the Journal of Pediatrics.
Playing an MP3 player at full blast could harm the hearing. Parents should look for signs of a problem, like when a child complains of ringing in the ears or sounds being muffled.
Prolonged exposure to sounds louder than 85 decibels (dB) can cause gradual hearing loss. A normal conversation is about 60 dB. Many personal stereo systems at maximum level are over 100 dB. Rock concerts and firecrackers can be 140 dB and higher. Noise levels need to reach 120 dB to 140 dB to become uncomfortable or painful.
Manufacturers, should equip MP3 players with an indicator that displays the volume level in terms of decibels, along with a signal –– such as a flashing light –– that goes off when decibel levels reach the danger zone.
Noise–induced hearing loss usually happens slowly, with no pain. Right after exposure to noise, you may notice some "ringing" in your ears. You might have trouble hearing people talk. After several hours or even a few days, these symptoms may go away. However, when you are exposed to loud noise repeatedly, you could have hearing loss that lasts forever.
The louder the sound, the shorter the time period before noise induced hearing loss can occur. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. A good rule of thumb is to avoid noises that are "too loud" and "too close or that last "too long."
For average factory noise, 85 dB, it takes only 8 hours for noise–induced hearing loss (NIHL). Other excess levels include: passing motorcycle, 90 dB–8 hours exposure for NIHL, subway train or diesel truck, 100 dB–2 hours exposure , helicopter and power mower 105 dB 1 hour, and, ranking with auto horn, propeller aircraft, and air raid siren, live rock music 90–130 dB 20 minutes.
Listening to music/muzak at 110 to 120 decibels damages hearing in less than an hour and a half.
iPOD guidelines
- A typical person can safely listen to an iPod for 4.6 hours per day at 70 percent volume using stock earphones.
Listening to music at full volume through an iPod for more than five minutes a day using stock earphones can increase the risk of hearing loss in a typical person.
Individuals can safely listen to iPods for 90 minutes a day with the supplied earphones if the volume is at 80 percent of maximum levels without greatly increasing the risk of hearing loss.
The safest limit is 2 hours a day at 50% of the volume.
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