Sound absorbing materials for walls are vital to reduce the reverberation of sound and noise within rooms. Sound absorbing materials absorb incident sound rather than deflect it with a hard surface and are available in a wide range of acoustic finishes and designs. However, it is important to understand what makes a material sound absorbing in order to make the right choice. There are two ratings used to classify a soundproofing material – its noise reduction coefficient (NRC) and its sound transmission class (STC).

The NRC rating measures how effective a material is at reducing noise from a specific frequency; the STC rating measures how well it blocks noise between spaces. To achieve good acoustic performance both of these values need to be high but in different ways – the NRC for absorbing and the STC for blocking.

Creating Serenity: Sound Absorbing Materials for Walls

A sound absorbing material’s ability to reduce reverberation is dependent on its density, porosity, and cell structure. The density is the amount of mass packed into a given volume; the lower the density, the more likely the material will reflect sound waves and the higher it is, the more it will absorb them. The cell structure is how the material is composed; open cell arrangements are better absorbers and closed cells are better blockers.

Blown-in insulation or batt insulation is made of fiberglass, cellulose or foam and is mechanically blown or sprayed into wall, floor or attic cavities to provide thermal and sound insulation. These materials are usually a good choice for insulating against sound transmission but can be less effective as a standalone sound absorbing solution.