noise exposure can cause noise induced hearing loss (NIHL). Such
loss can occur gradually over a number of years or occur as the
result of a one time acoustic trauma.
- Noise induced hearing loss begins subtly and is often not recognized
by the individual. The first indication is a temporary shift in
hearing ability before and after exposure. This is termed a temporary
threshold shift (TTS). It is termed "temporary" because
hearing returns to normal after a period of time away from the
noise that caused the shift. However, over time with repeated
exposure, the temporary threshold shift become a permanent threshold
shift (PTS). PTS is permanent, irreversible sensorineural loss.
Trauma - Hearing loss due to acoustic trauma is caused
by head or ear trauma or a one time exposure to a very intense
sudden noise, such as an explosion. The eardrum can be perforated
or the middle ear ossicles affected. Usually, this type of hearing
loss is temporary and recoverable.
noise induced hearing loss begins slowly and imperceptibly to the
individual, limits have been set for occupational exposure to noise.
These exposure limits are established in the United States by the
Occupational Safety and Health Administration (OSHA).