Soundproofing works by using materials and techniques that absorb, block, or dissipate sound waves to reduce noise transmission between spaces. It combines several acoustic principles to achieve optimal results.
Basic Principles
Sound Absorption
Absorbing materials, like acoustic foam or mineral wool, capture sound energy and convert it to heat. These materials are particularly effective at reducing echo and reverberation inside a room.
Sound Blocking
Dense and heavy materials, like multi-layer gypsum or mass-loaded panels, physically block sound transmission. The denser a material, the more difficult it is for sound waves to pass through.
Decoupling
Decoupling involves physically separating surfaces to prevent direct vibration transmission. For example, staggered stud walls or floating floors significantly reduce sound transmission.
Types of Noise
Airborne Noise
Airborne noise travels through air (voices, music, television). It is generally treated by adding mass and absorption in walls, ceilings, and floors.
Impact Noise
Impact noise is caused by direct physical contact (footsteps, falling objects). It requires decoupling solutions like acoustic underlays or floating floor systems.
Soundproofing Materials
Mineral Wool
Rock wool or fiberglass is excellent for absorbing sound. It is often used in wall and ceiling cavities to reduce sound transmission.
Acoustic Foam
Acoustic foam is designed to absorb sound waves and reduce reverberation. It is often used in recording studios and home theaters.
Spray Foam
Spray foam offers not only excellent thermal insulation but also helps reduce sound transmission thanks to its cellular structure and air-tight seal.
Soundproofing Ratings
STC Rating
The Sound Transmission Class (STC) measures how effectively a wall blocks sound. The higher the rating, the better the soundproofing. A typical wall has an STC of about 35, while a well-soundproofed wall can reach 55 or more.
IIC Rating
The Impact Insulation Class (IIC) specifically measures the reduction of impact noise through floors. The Building Code generally requires a minimum IIC of 55 for residential units.