Hearing and Noise Reduction Overview
According to the World Health Organization noise-induced hearing loss (NIHL) is the most common, permanent, and preventable occupational injury in the world.
Noise damage is different from most other occupational injuries. It causes no pain or visible trauma, the ears do not bleed when hearing is being damaged, it leaves no visible scars, it is unnoticeable in its earliest stages, it accumulates with each
over-exposure, and it generally takes years to diagnose.
Damage occurs as sound waves from high noise levels enter your ear canal and cause the eardrum to vibrate. Small bones behind your eardrum transmit these vibrations to the cochlea. Receptor cells in the cochlea convert these vibrations into electrical
impulses and send them to your brain. These vibrations are then interpreted as sound. When high noise levels damage your hearing it does not damage the eardrum or bones. Loud noise damages the receptor cells in the cochlea overtime. Unlike other
cells in your body that can regenerate, nerve cells in the cochlea, once damaged, are gone forever.
So if somebody has hearing loss, how can we tell whether it is caused by noise? Here are the five common indicators of noise-induced hearing loss:
- The amount of time exposed to loud noise. There is no delayed effect in regards to noise damage.
- It is almost always a high-frequency hearing loss.
- It is usually bilateral (affects both ears equally). There are some exceptions to this but for employees who are on their feet during the workday; the hearing loss is usually in both ears equally.
- Gradual progression. We don’t measure hearing loss due to noise in terms of days or weeks. It usually takes us years to notice the permanent change in hearing.
- Appropriate symptoms. If a worker says he has pain in his ears or drainage this is probably not due to high noise levels. Ringing in the ears, tinnitus is a common symptom that is linked to noise-induced hearing loss.
Basically If you experience a ringing or humming in the ears after work, inability to communicate with a co-worker when only an arm's length away, and/or temporary hearing loss at any time the background noise is most likely hazardous.