Maximum length sequence and Bessel diffusers using active technologies.
Cox, TJ, Avis, MR and Xiao, L 2006, 'Maximum length sequence and Bessel diffusers using active technologies.' , Journal of Sound and Vibration, 289 (4-5) , pp. 807-829.
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Active technologies can enable room acoustic diffusers to operate over a wider bandwidth than passive devices, by extending the bass response. Active impedance control can be used to generate surface impedance distributions which cause wavefront dispersion, as opposed to the more normal absorptive or pressure-cancelling target functions. This paper details the development of two new types of active diffusers which are difficult, if not impossible, to make as passive wide-band structures. The first type is a maximum length sequence diffuser where the well depths are designed to be frequency dependent to avoid the critical frequencies present in the passive device, and so achieve performance over a finite-bandwidth. The second is a Bessel diffuser, which exploits concepts developed for transducer arrays to form a hybrid absorber–diffuser. Details of the designs are given, and measurements of scattering and impedance used to show that the active diffusers are operating correctly over a bandwidth of about 100 Hz to 1.1 kHz. Boundary element method simulation is used to show how more application-realistic arrays of these devices would behave.
|Themes:||Subjects / Themes > Q Science > QC Physics > QC221-246 Acoustics - Sound|
Subjects outside of the University Themes
|Schools:||Colleges and Schools > College of Science & Technology > School of the Built Environment|
Colleges and Schools > College of Science & Technology > School of Computing, Science and Engineering > Acoustics Research Centre
|Journal or Publication Title:||Journal of Sound and Vibration|
|Depositing User:||H Kenna|
|Date Deposited:||10 Sep 2007 14:01|
|Last Modified:||07 Nov 2011 10:58|
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