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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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    Abstract

    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.

    Item Type: Article
    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
    Publisher: Elsevier
    Refereed: Yes
    ISSN: 1095-8568
    Depositing User: H Kenna
    Date Deposited: 10 Sep 2007 14:01
    Last Modified: 20 Aug 2013 16:47
    URI: http://usir.salford.ac.uk/id/eprint/428

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