The Process – Acoustics

When it comes to flooring, the more muffled the sound, the better, especially in a multi-story building, house, apartment, or condominium. Fortunately, there are a couple of good underlayment choices with effective sound dampening properties.

Sound is transmitted when hard objects, like hard-soled shoes, furniture, dropped objects, or even dog claws impact a hard surface, like wood flooring. Without anything to absorb it, sound waves can spread, multiply, and echo off the walls, amplifying even a small sound to a distracting crescendo with the right acoustics. Given a large room with high ceilings and hard polished floors, a simple walk across the lobby of an office building, for example, can become quite a distraction.

Sound transmission is rated using three different standards, each defining a different way in which sound is transmitted. Sound absorption of floor coverings may be measured on two of those scales. The third covers room-to-room transmission, more appropriate for walls.

  1. IIC (impact insulation class) is measured in terms of sound impact, or how well sound vibrations travel through a floor to the room below.
  2. STC (sound transmission class) is measured in terms of sound transference such as speech, television, dogs barking, and other similar annoyances.

Cork: is a great choice for sound reduction. It does more than merely dampen sound; it absorbs it, creating a blissful peace that everyone will appreciate, including downstairs neighbors. Cork is such an effective sound reduction material that it is used on walls to soundproof recording studios to produce clear soundtracks without background noise. The key is in the porous structure of the cork. Rather than bounce around, sound waves sink into the cellular structure of the cork and are broken up.

In addition to the obvious benefit of sound reduction, cork underlayment adds a slightly springy give that makes it comfortable and easy to walk or stand on and may even save dropped objects from breaking on impact. Cork comes in ¼” and ½” thicknesses. The IIC rating is 54 and the STC rating is 59 over 5/8″ plywood when the wood flooring is glued down.