What causes sound to travel and how to effectively prevent it
Airborne noise is sound that travels through the air as pressure waves, and can be produced by a variety of sources, including speakers, engines, and human voices.
The intensity of airborne noise is measured in decibels (dB), and can range from very quiet levels like 30 dB to extremely loud levels exceeding 140 dB.
Airborne noise can be transmitted through walls, floors, and ceilings, and can be attenuated or reduced by using sound-absorbing materials or adding additional layers to structures.
Prolonged exposure to high levels of airborne noise can cause hearing damage, stress, and sleep disturbances, and can contribute to other health problems.
Impact noise is a type of sound that is generated by the impact or collision of two objects, such as footsteps, doors slamming, or objects dropping on the floor.
Unlike airborne noise, which travels through the air, impact noise is transmitted through the building structure, such as floors, walls, and ceilings.
Impact noise can be particularly disruptive, as it can be heard more loudly and clearly in adjacent rooms or units, and can even cause vibrations that can be felt.
The intensity of impact noise is also measured in decibels (dB), and excessive exposure can cause hearing damage, stress, and sleep disturbances.
To reduce impact noise transmission, soundproofing materials, such as acoustic underlayment or resilient channels, can be installed in floors and walls.
Contractors are offering to soundproof walls by injecting insulation into stud cavities inside the wall. They offer this approach as low-cost, low-mess soundproofing. This approach has only one problem; it does not work in most situations.
Look at the Ontario building Code 2012 MMAH Supplementary Standard SB-3. This document lists hundreds of wall and ceiling assemblies derived by testing at the National Research Council of Canada.
Here are some STC values published in the standard.
STC without insulation
STC with insulation
Wood stud 89 mm wall; 1 layer of 12.7 mm gypsum board on each side
Wood stud 89 mm wall; 1 layer of 15.9 mm gypsum board on each side
Wood stud wall; 2 layers of 15.9 mm gypsum board on each side
Wood stud 89 mm wall; 2 layers of 15.9 mm gypsum board on each side; resilient channels on one side
Wood stud 89 mm wall; 2 layers of 12.7 mm gypsum board on each side; resilient channels on one side
Steel stud 92 mm 406 mm o.c. wall; 1 layer of 15.9 mm gypsum board on each side
Steel stud 92 mm 406 mm o.c. wall; 2 layers of 15.9 mm gypsum board on each side
1) Adding insulation to a typical wood frame wall with drywall or lath and plaster on each side will improve the STC value by 2 to 4 STC points. A hardly noticeable and inadequate improvement in most situations.
2) Customers often want to improve noise resistance by at least 10 STC points, reducing the noise level to one-half. Blowing insulation into wood frame walls does not come close to that objective. Steel frame walls can be improved by adding insulation by a moderate 9 to 10 STC points.
3) The only way of getting STC 52 or more with a single wood frame wall is by including resilient channels and insulation.
(Source: The Soundproofing Expert)
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