Deafness induced by exposure to noise is a problem that is of great concern nowadays in noisy environments. It is common experience that exposure to loud sound can produce hearing loss. For sounds of moderate intensity the loss can be temporary and as recovery is complete the loss is called Temporary Threshold Shift. It is interesting to note that the band of frequencies between 3000 Hz and 5000 Hz is the last to return to normal from such a shift. This frequency range is in fact particularly liable to be damaged by noise exposure and as the levels of noise and the exposure time are increased, there comes a point where the hearing never recovers and permanent hearing loss is incurred. It is in the region of 5000 Hz that the damage first becomes permanent. The level of sound and length of exposure for the damage to become permanent is not certain and is the subject of much investigation by people concerned with preventing hearing loss caused by noisy environments.
There is evidence that temporary dullness of hearing and Tinnitus (ringing noises in the ear)) can follow the use of headphone listening. These symptoms can sometimes take days to disappear and it is generally accepted that they should be treated as warnings that permanent damage could occur if the same listening habits were to continue over a period of years.
Your hearing is not indestructible. It is part of your livelihood and must be protected. If you can't hear properly you will not be able to do your job properly.