Noise and Prevention
Exposure to loud noise over a long period of time will damage the sensitive nerve endings in the cochlea and result in a permanent sensorineural hearing loss. It usually occurs gradually over a long period of time and tends to affect the higher pitched tones. You may find it difficult to hear a watch ticking or a kettle whistling.
Gradually the lower pitched sounds will be affected as well. When this occurs speech will
become difficult to understand, sounds will be muffled and ringing in the ear may become permanent.
Loss may also occur very suddenly if you are exposed to a loud explosion, blast or shot from a gun. The Canadian Hearing Society has conducted extensive research regarding noise and the effect it has on hearing ability. Noise levels are measured in DECIBELS (db). The louder the noise, the higher the decibel level and the greater the risk of permanent damage.
Sound Level and Human Response
| COMMON SOUNDS | NOISE LEVEL (db) | EFFECT |
|---|---|---|
| Jet engine (near) | 140 | Threshold of pain |
| Shotgun firing | 130 | Threshold of pain |
| Power saw Pneumatic drill Rock music band | 110 | Regular exposure of more than 1 min. risks permanent hearing loss |
| Garbage truck | 100 | No more than 15 min. |
| Motorcycle | 90 | Very annoying, damage begins (8 hrs.) |
| Many industrial work places | 85 | Level at which hearing damage begins |
| Average city traffic | 80 | Annoying, interferes noise with conversation. |
| Vacuum cleaner | 70 | Intrusive |
| Normal conversation | 60 | |
| Quiet office | 50 | Comfortable |
| Whisper | 30 | Very quiet |
To prevent noise induced hearing loss following precautions should be taken:
- Walkman, ghetto-blasters, stereos and radio headsets sound be kept at a low volume
- Use ear plugs when attending loud rock concerts and clubs, operating noisy machinery, or working on industrial sites
Background noise is too loud if:
- you find that you have to shout to be heard, as you do in a place when loud music is playing or around machinery
- you cannot hear conversation more than two feet away from you
- you find that certain noises hurts your ears
- your ears ring after you leave a noisy place
- you do not hear well after exposure to a loud noise and find that your ears are DULL
Consequences of Exposure to Loud Noise
This photograph shows cochlear hair cells after three hours of exposure to rock music at 105 - 125 db. The result is damage ('moth-eaten' appearance) to the hair cells that are responsible for sending the sound message to the brain.