How Sound Absorption Works

By Author: Kevin Richard
Total Articles: 240
Comment this article

Proper sound absorption is one of the vital qualities of any soundproofing material. You can get a great idea about the principle of sound absorption by listening to your voice in the hall, then going into the bedroom or sitting room and collating these changes.

This difference depends on what happens to the noises that you make when they come in contact with a floor, wall or a sound absorbing fabric.

The best soundproofing products and materials are the ones that absorb maximum amount of sound. As a thumb rule, the most absorbent materials are porous, implying that the structure of the material basically traps the moving waves of air. Fabrics, for instance, have a tendency to make efficient sound absorbing surfaces as the fibers conveniently trap the waves rather than allowing them to bounce back. The same is also applicable for foam. The structure of the material is extremely good in trapping waves as they hit it, and this makes it a good option for sound insulation.

You can imagine ...
... sound waves as a series of small balls, which may bounce back from solid surfaces such as concrete, but would rather get trapped in. For instance, consider a surface or a net with many gaps in it. As less sound balls bounce back from the latter surface, you would hear less sound and hence have a higher level of sound absorption.

This is how sound insulation works for airborne sound, or sound that travels through the air and hits the surface. But sound is also transmitted through the surfaces. You may hear transmitted sound when somebody is walking on the floor above and you hear them through the ceiling. To lessen transmission, it is important to break the normal routes that sound takes. Imagine the difference between the balls rolling down a slope and through dense glass. Then again, the energy of the sound should be absorbed.

Once a sound wave or outdoor sounds are caught in a material with good sound absorption qualities, the energies in that sound wave just will turn to heat. Not much heat, obviously, and the energy absorbed from a loudly playing album would barely be one hundredth of the heat of a match. Moreover, a material with good heat absorption qualities won’t necessarily provide proper sound absorption. Polystyrene insulation, for instance, will trap heat effectively but fail to absorb much sound.

It is also worth mentioning the various frequencies of sound need various options of sound insulation through fire rated wall assemblies. The biggest factor is the density, and as a thumb rule, the denser the material, the deeper the frequency of the sound that will be absorbed.

Last but certainly not the least, if you are quite proactive with your sound treatment, then you should look for an acoustic cloud solution.