The Variable Room Acoustics System is an
acoustic enhancement Acoustic enhancement is a subtle type of sound reinforcement system used to augment direct, reflected, or reverberant sound. While sound reinforcement systems are usually used to increase the sound level of the sound source (like a person speakin ...
system for controlling room acoustics electronically. Such systems are increasingly being used to provide variable acoustics for multipurpose venues.
VRAS uses multiple microphones distributed around the room, fed via a multichannel digital reverberator to multiple loudspeakers to provide controllable enhancement of the reverberation time of the room. It is an example of a non-in-line or regenerative sound system which uses the inherent feedback of sound from the loudspeakers to the microphones to enhance the reverberation time for all sound source positions within the room. VRAS uses a unitary reverberator which maintains a constant power gain with frequency so that its inclusion does not affect the stability of the system (at each frequency the reverberator is a
unitary matrix
In linear algebra, a complex square matrix is unitary if its conjugate transpose is also its inverse, that is, if
U^* U = UU^* = UU^ = I,
where is the identity matrix.
In physics, especially in quantum mechanics, the conjugate transpose is ...
).
[ M. A. Poletti, ”The stability of single and multichannel sound systems,” Acustica-Acta Acustica, vol. 86, pp 123-178, 2000/ref>
In addition, VRAS uses a number of microphones close to the stage area to detect early energy from the performers, which is used to generate early reflections. Such systems are termed in-line or non-regenerative. In-line systems aim to minimise the effects of regeneration by detecting stage sound at a high level, and may then be used to generate early reflections or late reverberation.
VRAS is thus a hybrid system that uses both regenerative and non-regenerative approaches.
VRAS was developed by Mark Poletti a]
Industrial Research Limited
New Zealand and commercialized by LCS Audio. VRAS is now a part of th
Meyer Sound Laboratories
Constellation System.
See also
*Architectural acoustics
Architectural acoustics (also known as building acoustics) is the science and engineering of achieving a good sound within a building and is a branch of acoustical engineering. The first application of modern scientific methods to architectura ...
*Reverberation
Reverberation (also known as reverb), in acoustics, is a persistence of sound, after a sound is produced. Reverberation is created when a sound or signal is reflected causing numerous reflections to build up and then decay as the sound is abso ...
*Room acoustics
Room acoustics is a subfield of acoustics dealing with the behaviour of sound in enclosed or partially-enclosed spaces. The architectural details of a room influences the behaviour of sound waves within it, with the effects varying by frequency. ...
References
Technical Papers
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* M. A. Poletti, “An assisted reverberation system for controlling apparent room absorption and volume,” 101st convention of the Audio Engineering Society, Los Angeles, November 8–11, 1996
* M. A. Poletti, “A comparison of passive and active coupled rooms for acoustic control” Internoise 98, Christchurch 16–18 November
* S. Ellison and M. Poletti, "Variable Room Acoustics System: Philosophy and Applications", Proc. Institute of Acoustics, Volume 22 Pt 6 2000, p 215-223
* S. Ellison and M. A. Poletti, Control of room acoustic parameters by the Variable Room acoustics System, Reproduced Sound 2004
* M. A. Poletti and R. Schwenke, “Prediction and Verification of Powered Loudspeaker Requirements for an Assisted Reverberation System,” 121st AES Convention 2006 October 5–8, San Francisco, CA, USA
External links
Meyer SoundIndustrial Research Limited
{{DEFAULTSORT:Vras
Sound production technology