Hearing impairment doesn't happen overnight: it sneaks up on people as they become accustomed to being exposed to noise every day. Hearing impairment is therefore a very gradual process that passes almost unnoticed, but once it happens it is irreversible. Hearing impairment only becomes noticeable when people start hearing less. Hearing impairment is caused when the hair cells in the inner ear die off and are no longer replaced. Hearing improvement cannot be reversed with an operation.
Hearing can be damaged at noise levels in excess of 80 dB(A). Some examples of noise sources:
People can be exposed to noise in excess of 80 dB(A) for only a limited amount of time before there is a chance of their hearing being impaired. For example: a person can be exposed to a noise level of 95dB for just 15 minutes and 98dB(A) for just 7.5 minutes. This example also illustrates the fact that if the noise level increases by 3 dB(A) the permissible noise exposure duration without hearing protection halves.
Research has shown that as well as causing hearing impairment noise leads to other physical disorders such as raised blood pressure, nervousness and fatigue. Using effective hearing protection is therefore very important to preventing or eliminating these problems!