Diffuse sound field - A sound field in which the sound pressure level is the same everywhere and the flow of energy is equally probable in all directions.

Diffraction - The bending of a sound wave around an obstacle, or through an opening, such as slats. The scattering of sound Wavesat an object smaller than one wavelength, and the subsequent interference of the scattered wavefronts.

De-Coupling - See Isolation.

Decibel (dB) - The measuring unit of sound pressure, and hence loudness. The decibel is a numerical ratio between the sound pressure of a given sound and the sound pressure of a reference sound (usually .0002 microbar).

Decay time

Dead - An acoustical condition in which reverberation is absent, as in a room whose surfaces are covered with highly absorptive materials.

Damping - The loss of energy in a vibration system, usually through friction.

D-Ring - A metal mounting device, shaped like a D, used in conjunction with hanger wire to mount baffles.

Cycles per second - The frequency of an electrical signal or sound wave, measured in Hertz (Hz).

Cycle - A complete positive (forward) and negative (backward) movement of a vibration corresponding to a high and low pressure wave.