NOISE?
Noise is unwanted sound, produced by mechanical means which is transmitted through the air in the form of sound waves.
A sound wave is a series of high and low pressure regions. We hear because our eardrums vibrate in response to these changes in the air pressure.
Sound is measured in decibels, or dB. The A-Weighting Filter (dBA) is used to simulate what the human ear hears. Three factors that influence the measurement of sound are: a. Noise generating conditions. b. Distance from source. c. Other background sound sources.
| Noise Level Comparison | dBA | Conversation Level Comparison |
| Jet Plane Take Off | 140 |
x256 |
| Pain Treshold | 130 | x128 |
| Chainsaw | 120 | x64 |
| Rock Group | 110 | x32 |
| Police Siren |
100 |
x16 |
| Truck | 90 |
x8 |
| Vacuum Cleaner |
80 | x4 |
| Busy Restaurant |
70 | x2 |
| Busy Office | 60 | Normal Speech |
| Backstreet | 50 | x1/2 |
| Library | 40 | x1/4 |
| Nighttime | 30 | x1/8 |
| Sound Studio | 20 | x1/16 |
| Testing Room | 10 | x1/32 |
| Hearing Threshold | 0 | x1/64 |
| Exposure to Noise before Possible Hearing damage |
||
| Duration of Exposure per Day |
Sound Level (dBA) |
|
| 8 hours |
85 | |
| 4 hours |
88 | |
| 2 hours |
91 | |
| 1 hour | 94 | |
| 30 min |
97 | |
| 15 min |
100 | |
| 8 min | 103 | |
| 4 min |
106 | |
| 2 min | 109 | |
| 1 min | 112 | |
| 30 sec | 115 | |