The qualities of a space that reflect or absorb sound waves.

Further Reading

Baux, The Book of Acoustics Making People Happy at Work, (Vulkan, 2021). www.baux.com/book-of-acoustics/.

The goal of acoustic design is to serve the space’s intended function and the users’, collective needs. Understanding how sound works is key to creating an environment that is supportive of how the space functions. When a sound wave is produced, it travels and bounces off the reflective surfaces it comes in contact with. The amount of time it takes (in seconds) for that sound energy to dissipate is called “reverberation time” (RT).

The reverberation of a sound wave is affected by all surfaces and contents within a room, including the flooring, furniture, window treatments, and even people. In a space containing hard and reflective walls, floors, and ceilings, sound waves bounce around the room multiple times before they become inaudible, resulting in an echoey room.

Lengthy reverberation times allow sounds to build up and conflict with one another. Ideal reverberation times can vary based on how the space is used; however, a range from around 0.6 to 0.8 seconds is ideal for an office space. Short RTs (under 1 second) are preferable for high-quality intelligibility in private offices, meeting rooms, and classrooms.

Designers can’t always control the sound that takes place in a space, but they can specify materials and products that absorb, block, cover, or diffuse sound, which reduce reverberation time to an acoustically comfortable range.

The Noise Reduction Coefficient (NRC) is a value ranging from 0.0 to 1.0 that measures sound-absorption performance of materials.