A
reverberation chamber or room is a room designed to create a
diffuse
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
or random incidence sound field (i.e. one with a uniform distribution of acoustic energy and random direction of sound incidence over a short time period). Reverberation chambers tend to be large rooms (the resulting sound field becomes more diffused with increased path length) and have very hard exposed surfaces. The change of
impedance (compared to the air) these surfaces present to incident sound is so large that virtually all of the acoustic energy that hits a surface is reflected back into the room. Arranging the room surfaces (including the ceiling) to be non-parallel helps inhibit the formation of
standing waves
In physics, a standing wave, also known as a stationary wave, is a wave that oscillates in time but whose peak amplitude profile does not move in space. The peak amplitude of the wave oscillations at any point in space is constant with respect ...
- additional acoustic
diffusers are often used to create more reflecting surfaces and further encourage even distribution of any particular sound field.
Reverberation chambers are used in acoustics as well as in electrodynamics, such as for
measurement microphone calibration, measurement of the
sound power
Sound power or acoustic power is the rate at which sound energy is emitted, reflected, transmitted or received, per unit time. It is defined as "through a surface, the product of the sound pressure, and the component of the particle velocity, at ...
of a source, and measurement of the
absorption coefficient
The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. A coefficient valu ...
of a material. All these techniques assume the sound field in the chamber to be diffuse, and will normally use a broadband sound source (e.g.
white noise
In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines ...
or
pink noise
Pink noise or noise is a signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave interval (halving ...
) so that the resulting sound field contains acoustic energy across the whole audible range.
See also
*
Anechoic chamber
An anechoic chamber (''an-echoic'' meaning "non-reflective") is a room designed to stop reflections of either sound or electromagnetic waves. They are also often isolated from energy entering from their surroundings. This combination means t ...
, an acoustic test facility which minimizes reverberation
*
Echo chamber
Echo chamber of the Dresden University of Technology
Hamilton Mausoleum has a long-lasting unplanned echo
An echo chamber is a hollow enclosure used to produce reverberation, usually for recording purposes. For example, the producers of ...
, a reverberation room used for music recording
*
Electromagnetic reverberation chamber
An electromagnetic reverberation chamber (also known as a reverb chamber (RVC) or mode-stirred chamber (MSC)) is an environment for electromagnetic compatibility (EMC) testing and other electromagnetic investigations. Electromagnetic reverberatio ...
, an
electromagnetic
In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions o ...
environment mainly for
electromagnetic compatibility testing
References
ISO Standard for Measurement of Acoustic Absorption in a Reverberation Room
External links
360 video of a reverberation chamberPictures and further description of a reverberation chamber
Acoustics
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