Loud noises can have a negative impact on one’s hearing and can lead to permanent hearing loss. The higher the noise the higher the risk of damage. Thus, less time passes in which one can tolerate the noise before the damage is done.

To many, the idea that listening to loud noises for a long period of time can cause hearing damage sounds like simple, common sense. But what is perhaps not so clear is the way in which sounds are measured. They are measured in decibels on a logarithmic scale. This means that one more decibel is equal to a much higher sound level. The sound level actually doubles with every three decibels. This also means that just a few more decibels dramatically shortens the time in which one can listen to a sound without it leading to hearing damage.

Louder noises = shorter time

If you put the volume on your MP3 player on a medium setting, that is the same as around 85db, which the ears can tolerate for around eight hours. If you turn the volume up to 88db, the ears can only tolerate such a level for around four hours. On maximum volume, many portable music devices will reach a level of 120db. This means that your ears can be damaged after only eight seconds. 120db is equal to the jet engine of a large plane taking off.

In other words, the sound level doubles between 85db and 88db and therefore halves the time in which one should listen to music. One should be aware that just a slight turn of the volume dial means a much shorter time in which one can listen to music if one is to avoid the risk of damage.

Source: http://www.hear-it.org/page.dsp?page=7228