As many as 46,000 teenagers underwent treatment for hearing difficulties last year. This marks a 50 percent jump in four years. Students should be careful when listening to music through headphones using their smartphones and other portable devices.

The number of hearing-impaired teens has grown twice as fast as that of senior citizens. This breaks the myth that hearing ailments is limited to the elderly.

Hearing loss is prevalent among students habitually listening to music through earphones. They often put earphones in when going to and from school and private tutoring institutes and even when they are alone. They often jack up the volume to the highest possible level in order to avoid outside disturbances.

Doctors warned that noise-induced deafness will hit lovers of music at more than half of the maximum volume level. In the worst case, restoring auditory nerves becomes impossible.

Listening to music through earphones at the maximum volume can reach 100 decibels, equal to the noise level people hear when airplanes take off. This compares with the noise level of 80 decibels on expressways.

The noise level is 85-86 decibels when people listen to music through earphones at half of the maximum volume. The decibel jumps to 117 when the volume hits maximum. This is louder than the noise people experience in drilling concrete walls at construction sites.

Record companies have raised the sound volume by 10 decibels to upgrade sound quality over the past two decades.

Like the European Union, Korea should also regulate the maximum level to less than 100 decibels. The European Union recommends labels set the level below 85.