Background Noise
Background noise is a definition of all kinds of sound beyond the particular sound wanted.

Baffle
A flat board or plate, deflector, guide or similar device. In acoustics free installed baffles of absorbing material (e.g. mineral wool) can be used to control the room acoustics or can be mounted in a ventilation duct to attenuate airborne sound.

Bandwidth
The range of frequencies, expressed in Hertz (Hz), for the filters used for the frequency spectrum analysis. Often used bandwidth are 1/1 octave band or 1/3 octave band, but also 1/12 octave band.

Broadband noise
In the frequency domain, a broadband noise has a continuous spectrum - that is, energy is present at all frequencies in a given range. This type of sound is often referred to as noise because it usually lacks a discernible pitch. White noise and pink noise are typical broadband noises used for  acoustic measurements.