Sound Deadening Principles

Home comfort invariably rests on the quality of the building materials you choose. One aspect of comfort that has been most neglected in recent years is the quietness of the indoor environment.

The sound deadening and acoustic properties of the home should keep the hustle of modern life outside and convert the indoors into a veritable oasis of quiet. This quality alone is why many people choose to purchase a newly constructed home or renovate an existing one.

There are significant differences in the phonic absorption capacity between various materials. As opposed to synthetic insulation for example, which has no impact on sound transmission, all wood fibre insulation panels such as Enermax for the exterior and interior significantly reduce the level of noise transmitted.

Sound Transmission Class (STC) is the rating of airborne sound transmission and describes the degree of sound isolation provided by a home construction and materials. Outdoor-Indoor Transmission Class (OITC) is a used to indicate the rate of sound transmission between outdoor and indoor spaces, through walls, doors and windows. It can be used to measure sounds such as low flying airplanes, police sirens, and other such outdoor noise.

There are four principle methods used in soundproofing:

1. Mass
2. Air barrier
3. Insulation
4. Mechanical decoupling

Mass

Simply put, the denser a structure, the more difficult it is for sound to penetrate. As such, a concrete wall with grouted cores will stop noise much more effectively than wood or drywall. Adding an extra layer of drywall to a room with a single wood stud wall will yield an improvement of 4-5 dB.

Air barrier

By using an air barrier, you reduce the amount of sound transmission between your walls. This is evident immediately when you open a door or a window and listen to the outdoor noise. Double-glazed windows (windows with two layers of glass separated with a spacer) are mandatory according to the National Building Code of Canada. Triple-glazed windows can help reduce sound transmission. Ventilation, ducts and other openings can let through sound. Higher frequency noise can also travel through cracks, so it's best to find and seal them.

Insulation

The addition of insulation to a wall cavity blocks the flow of air and sound. Insulation, however, has no effect on structural noise such as vibration of a washer and dryer or heating, cooling and ventilating systems. Insulation works best in preventing transmission of mid and high frequency noise, but does not do well in preventing low frequency noise such as the bass of a subwoofer.

Mechanical decoupling

Sound passes through solid materials. Disconnecting the two sides of a partition will prevent noise by isolating it, thus decreasing vibrations and increasing sound deadening. There are different methods of achieving this, such as use of resilient channels and staggering the joints between panels of drywall. Soundproofing panels like Enermax must also be staggered with the drywall panel.