What are the symptoms of Noise-Induced Hearing Loss?

The symptoms of NIHL increase gradually over a period of continuous exposure.
Sounds may become distorted or muffled, and it may be difficult for the person to understand speech. The individual may not be aware of the loss, but it can be detected with a hearing test.

People assume that if the symptoms go away, their ears have "bounced back" to normal. This is not really true. Even if there are no more symptoms, some of the cells in the inner ear may have been destroyed by the noise. Your hearing returns to normal if enough healthy cells are left in your inner ear. But you will develop a lasting hearing loss if the noise exposure is repeated and more cells are destroyed.
The first sign of a noise-induced hearing loss is not hearing high-pitched sounds, like the singing of birds, or not understanding the speech of women and small children. If the damage goes on, hearing declines further, and lower pitched sounds, including men's voices, become hard to understand.