At first, noise induced hearing loss (NIHL) is only temporary and the symptoms usually disappear after a few hours. However, if exposure to harmful noise levels occurs repeatedly over a prolonged period of time then the delicate hair cells of the inner ear may become damaged. Hearing loss then becomes permanent.
Sometimes a single exposure to extreme noise (over 140 decibels) may result in immediate permanent effects. This is called “traumatic” hearing loss. The key factors of level and frequency of the sound, duration of exposure and susceptibility of the individual will determine the extent of damage that is suffered.
As the level increases, so does the potential for hearing loss. The frequency or pitch of a sound, measured in hertz, also has an impact. Finally, as the period of exposure (duration) to a harmful sound gets longer, the greater the likelihood of hearing damage.