Absorbing airborne noise
Airborne noise is noise radiated from structures and/or machines. When a machine or a structure is encased or insulated, the sound level in this space increases considerably. If the casing is not fitted with absorbing materials, then the sound level in the casing can increase by 17 dB. This increase can be compensated by converting sound waves into warmth using friction. This friction can be created by adding absorption on the places where the sound wave is reflected. Insulation and casing of these noise sources will be explained in chapter on ‘Insulation of airborne sound’.
The absorption method depends on the situation. One product may be used for absorption inside a casing while the other is used to reduce the noise level in the opening of a casing. Naturally, the amount of absorption material is important for the reduction of the sound level. The reduction provided by a certain amount of absorption area is given below:
|
Absorption area (%) |
Increase in sound level (dB) |
|---|---|
|
5 |
13 |
|
10 |
10 |
|
20 |
7 |
|
50 |
3 |
|
80 |
1 |
|
100 |
0 |
Product range to absorb airborne noise:
ALGP
Phonisorb
Splitter attenuators