Structural waves propagating along a railway rail form an extended source of sound radiation. Using an equivalent source model the distribution of this sound in a horizontal plane is investigated and shown to consist mainly of sound propagation at a particular angle to the normal. This direction is determined by the ratio of the wavenumbers in the rail and in air. Due to the extended nature of the rail as a source, the spatial distribution of the sound field in the direction along the track does not lend itself to the use of a simple directivity factor. The consequences for the measurement of noise from the rail using a microphone array are then explored. It is shown that a microphone array focussed normal to the rail does not detect most of the sound radiated by the rail. By turning the focus angle, the sound detected becomes a maximum when this angle corresponds to the angle of propagation of the sound radiation. Measurements on a test track using artificial excitation and measurements during the passage of a train confirm these conclusions.


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    Title :

    The horizontal directivity of noise radiated by a rail and implications for the use of microphone arrays


    Additional title:

    Horizontale Richtcharakteristik des von einer Eisenbahnschiene abgestrahlten Geräusches und Folgerungen für den Einsatz von Mikrophon-Arrays


    Contributors:

    Published in:

    Publication date :

    2010


    Size :

    19 Seiten, 21 Bilder, 31 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English





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