Sound absorption means that the energy of the sound is converted into mechanical vibration and/or heat energy.
Sound absorption is expressed through the sound absorption coefficient (alpha) or the class A to E according to EN ISO 11654 and NRC/SAA, and according to ASTM C423.
Expressed in another way, as closer you get an absorption coefficient (alpha) near 1.0 – as more powerful is the “mute effect” in a given material.
What does the thickness?
The thickness of a sound absorber is not always decisive for how to achieve a good absorption.
Just think of a carpet. If you remove a carpet, there will often be a significant degrading of the acoustics, even though it is only a few mm thick.
The decisive factor to achieve good acoustics (absorption) is so to say; how many equivalent absorption squares there are in the room.
If a carpet is unwanted in a room, still, you can easily achieve good acoustics by mounting absorbers in the ceiling or at the walls.
A typical good ceiling absorber is often about 40 mm thick, and the best way of mounting is approximately 5 cm. from a wall, that is not directly on a wall surface (increases the reduction of the high frequencies).
What does the weight do?
Many have the opinion that the density of a material is essential for good sound absorption skills in a material. Basically, this is not correct, because weight itself does not absorb!
What promotes the absorption capacity is the structure of the material, and the ability to let airborne sound penetrate the surface without letting too much sound going directly through - and without reflecting too much on the surface you meet.
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Acoustic seen, the weight contributes to isolating the sound. A rule of thumb says that a doubling of the weight of a material (i.e. double thickness of a material) will lead to a reduction of 6 dB.
The weight can also have a positive influence on the damping of vibrations and tremors. Examples of heavy materials can be heavy foils or bitumen plates.
B6 Akustik offer numerous products and solutions that can all be fitted into metal parts in machines and cabins etc with the effect that the vibrations (structure sound) are removed - and consequently lead to a great experience of a better comfort.