Reverberation Chamber

A Reverberation Chamber reflects sound energy at every boundary and allows the field to diffuse fully within the room, so that the energy density is uniform throughout and the sound is distributed randomly in all directions. It is used principally to measure the absorption coefficient of materials, to measure sound absorption in air, to characterize the sound power and spectrum of sources and machinery, to evaluate the efficiency of electroacoustic devices, and to conduct noise fatigue testing on precision components.

The common volume is 70 to 300 cubic meters, with a standard chamber positioned at approximately 200 cubic meters within a tolerance of 10%. The lowest test frequency is 125Hz for one octave bands or 100Hz for one third octave bands, reverberation times range from a few seconds to tens of seconds, the average absorption coefficient remains no greater than 0.06, and the standard deviation of sound pressure across measurement points remains below 1dB.

To maintain a diffuse field, the room adopts an irregular set of proportions such that no two dimensions form a whole number ratio. The walls are finished with hard reflective surfaces such as enamel, tile or copper foil, and fixed diffuser panels together with large rotating diffusers may be suspended to further improve field uniformity.