Break - A physical gap in the assembly or construction, which acts to decouple sound vibrations from traveling through a structure.

Boomy / Boominess - Listening term that usually refers to an excessive amount of low frequency (bass) energy.

Block - To reduce airborne sound transmission.

Bass Trap - A low frequency absorber. Low frequencies are particularly difficult to absorb due to their long wavelengths. Bass traps are designed and constructed to absorb these longer Wavesand control unwanted room resonances. Broadband absorbers extending to lower frequencies are often called Bass Traps, imprecisely.

Barrier - Heavy, dense and massive material used to block sound.

Baffle - A device used to inhibit the propagation of sound waves. Baffles are usually suspended vertically from ceiling to reduce reverberation time.

Background noise - The ambient noise level above which signals must be presented or noise sources measured.

Axial mode - The room resonances associated with each pair of parallel walls (including ceiling and floor).

A-Weighted Sound Level - A measure of sound pressure level designed to reflect the response of the human ear, which does not respond equally to all frequencies, by reducing the effects of the low and high frequencies with respect to the mid-range frequencies. The resultant sound level is said to be A-weighted, and the units are dBA.

Audio frequency - A frequency that falls within the range of the human hearing, usually taken as 20 Hz to 20 kHz.