Airborne sound that is reflected against hard surfaces can be reduced by covering the surfaces with absorbents. Absorbents convert the airborne sound into small amounts of heat energy, thereby decreasing the perceived noise. Examples of sound absorbents include plastic foam, textile fibre and metal.
Another way of reducing the transmission of noise is by insulating the noise to its source. This can be done through the use of walls or hoods. The sound insulation capabilities of these components increase with their weights as well as their number of layers.
Structure-borne sounds are vibrations in solid materials generated by, for instance, machines. This type of sound can be dampened by applying pads to one or several sides of the noise-generating source. The pads serve to convert the vibration energy into heat.