LOCTITE - acoustic coatings - TEROSON
Basically, there are two options for controlling noise: insulation or absorption. As both options can be applied to airborne and to structure-borne sound, there are in fact four different types of noise control:
1. Absorption of structure-borne sound
Absorption of structure-borne sound is achieved by converting part of the sound energy into thermal energy while the sound travels through homogeneous materials attached or bonded to a solid body. In this way, the structure-borne sound is absorbed before it generates air-borne sound. The better the absorption properties of such damping materials, the better the structure-borne sound absorption. The “loss factor” is a parameter for measuring this effect.
2. Insulation against structure-borne sound
Insulation against structure-borne sound is achieved by attenuating the propagation of sound by using a flexible material for sound insulation. The softer and more voluminous this material, the better the structure-borne sound insulation.
3. Absorption of air-borne sound
Absorption of air-borne sound is achieved by converting part of the air-borne sound energy into thermal energy as the sound penetrates into fibrous or foam materials. The thicker the fibrous or foam materials, the better the air-borne sound absorption.
4. Insulation against air-borne sound
Insulation against air-borne sound is achieved when part of the sound energy is reflected by a wall. The remaining sound energy is transmitted through the wall and re-radiated on the opposite side in the form of air-borne sound. The heavier and more flexible the partitioning wall, the better the airborne sound insulation.
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Source: Henkel Ltd.