What are the best ways to reduce noise transmission between rooms?

1 What is noise transmission?

Noise transmission is the process of sound waves traveling from one room to another through various paths, such as air, walls, floors, ceilings, doors, windows, and ducts. Noise transmission can be measured by the sound transmission class (STC), which is a rating of how well a building element or a partition can block airborne sound. The higher the STC, the better the noise isolation. For example, an STC of 25 means that normal speech can be easily heard through the partition, while an STC of 60 means that loud speech can be barely heard.

2 How to increase STC?

One of the most effective ways to increase STC and reduce noise transmission is to add mass and density to the partitions. Mass and density increase the impedance of sound waves, making them harder to pass through. For example, you can add a layer of drywall, plywood, or cement board to the existing walls, floors, or ceilings. You can also use materials that have high mass and density, such as concrete, brick, or stone.

3 How to reduce flanking paths?

Another way to reduce noise transmission is to eliminate or minimize flanking paths, which are indirect paths of sound waves that bypass the main partition. Flanking paths can occur through gaps, cracks, joints, openings, or structural connections between partitions and other building elements. For example, sound waves can travel through the air gap between the wall and the floor, or through the ducts that connect different rooms. To reduce flanking paths, you can seal any gaps or cracks with acoustic caulk, tape, or foam. You can also use resilient or isolating materials, such as rubber, neoprene, or fiberglass, to break the structural connections and reduce the vibration transfer.

5 How to use sound masking?

A fourth way to reduce noise transmission is to use sound masking, which is the technique of adding a background noise to mask or cover up unwanted noises. Sound masking can be done by using white noise generators, fans, or HVAC systems. Sound masking can create a more uniform and consistent sound environment, which can reduce the perception and annoyance of noise transmission. Sound masking can also enhance speech privacy and confidentiality, which can be important in some settings, such as offices, hospitals, or hotels.

6 How to consult a professional?

The last way to reduce noise transmission is to consult a professional acoustician or a noise control engineer, who can assess the noise problem and provide customized solutions. A professional can perform a sound level measurement, a frequency analysis, and a STC test to determine the sources, paths, and levels of noise transmission. A professional can also design and install appropriate acoustic treatments, such as sound barriers, baffles, diffusers, or absorbers, to improve the noise performance of the rooms. A professional can also advise you on the relevant codes, standards, and regulations that apply to your building and your noise issue.