Experts are warning against excessive use of MP3 players because of the potential adverse impact on the listener's hearing. The risk of permanent hearing loss can increase with exposure of just five minutes a day to music at full volume.
The main culprits
Ear bud headphones are small ear pieces that can be inserted into the ear. They can boost the signal by as much as six to nine dB. That's about the difference between the sound of a vacuum cleaner and a motorcycle, according to Dean Garstecki, professor at Northwestern University in the United States.
The inherent risk of excessive volume when using ear bud headphones makes them more hazardous to use than the older and larger muff-type earphones, which used to be the standard with Walkman and portable CD players. The ear buds positioned inside the ears are not as efficient at blocking outside sounds as the cushioned headsets. As a result, the volume knob often gets an extra turn to drown out the outside noise. To make matters even worse, the loud noise from the earphones is produced right inside the ear.
Hearing advocates are pressing for people to turn down the volume. Researchers at Children's Hospital Boston recommend that no MP3 player should ever be used at full volume. Instead, the volume should be kept at no higher than 60 percent of the maximum and that it should be used for no more than about 60 minutes a day.