Application of the Local Plane Wave method to measure In-situ Sound Absorption using a Spherical Microphone Array

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    Abstract

    Former studies have shown that the Local Plane Wave (LPW) method can be used to measure the (effective) in-situ sound absorption coefficient of any surface. The LPW-method is based on a local plane wave assumption, in which the normal component of the sound field in each spatial coordinate is approximated by an incident and a reflected plane wave. This is contrary to conventional methods that rely on a known global sound field, like the impedance tube (plane wave) and reverberation room (diffuse field) methods. The LPW-method can therefore be applied in sound fields for which a model is not available. This has been numerically and experimentally validated using a probe consisting of 8 MEMS-microphones in an open cubical structure. In this paper, the LPW-method will be applied to a rigid spherical microphone array. The wellknown plane wave expansion in spherical harmonics will be used to formulate a local model of the sound field in the presence of a rigid sphere. The resulting model will be used to infer the sound field for the case the rigid sphere would not be present. The (effective) in-situ sound absorption coefficient is then computed from the parameters of this inferred sound field. Using numerical and experimental results, the validity and usefulness of the LPW-method to measure sound absorption using a spherical microphone array will then be shown.

    Original languageEnglish
    Publication statusPublished - 1 Jan 2017
    Event24th International Congress on Sound and Vibration, ICSV24 - Park Plaza Westminster Bridge Hotel, London, United Kingdom
    Duration: 23 Jul 201727 Jul 2017
    https://www.iiav.org/icsv24/index.php?va=viewpage&vaid=366

    Conference

    Conference24th International Congress on Sound and Vibration, ICSV24
    Abbreviated titleICSV24
    CountryUnited Kingdom
    CityLondon
    Period23/07/1727/07/17
    Internet address

    Keywords

    • Absorption
    • In-situ
    • LPW
    • Sonocat
    • Spherical array

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  • Cite this

    Consten, N., De Jong, A., & Wijnant, Y. (2017). Application of the Local Plane Wave method to measure In-situ Sound Absorption using a Spherical Microphone Array. Paper presented at 24th International Congress on Sound and Vibration, ICSV24, London, United Kingdom.