Gert Jansens
Katholieke Universiteit Leuven
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Publication
Featured researches published by Gert Jansens.
Journal of the Acoustical Society of America | 2002
Jean François Allard; Gert Jansens; Gerrit Vermeir; Walter Lauriks
A Rayleigh-type surface wave at an air–air saturated porous layer interface is predicted and detected experimentally in the audible frequency range. Applications of this surface wave for the metrology of sound-absorbing media are suggested.
Journal of the Acoustical Society of America | 2003
Jean-François Allard; Michel Henry; Vincent Gareton; Gert Jansens; Walter Lauriks
For locally reacting materials with a constant surface impedance, a classical method based on the work of Chien and Soroka [J. Sound Vib. 43, 9-20 (1975)] for measuring this impedance in situ around grazing incidence is currently used. A generalization of this work to include thin nonlocally reacting materials with a surface impedance noticeably dependent on the angle of incidence is performed. It is shown that the model by Chien and Soroka can be used, though the constant surface impedance must be replaced by the impedance at grazing incidence for the evaluation of the numerical distance. Measurements performed on a thin porous layer using this method are compared with measurements performed using the near-field acoustical holography method [M. Tamura, J. Acoust. Soc. Am. 88, 2259-2264 (1990)]. Other measurements performed on a fibrous layer are in good agreement with the predicted values of the impedance at grazing incidence.
Journal of the Acoustical Society of America | 2002
Gert Jansens; Walter Lauriks; Gerrit Vermeir; Jean François Allard
A simple asymptotic approximation with two parameters (the plane wave reflection coefficient and a correction factor) has been derived by Brekhovskikh and Godin [Acoustics of Layered Media II. Point Sources and Bounded Beams (Springer, New York, 1992)], for the spherical field reflected by nonlocally reacting surfaces. In the present work, an expression for the correction factor is obtained for the case of a homogeneous and isotropic porous layer. A free field method for evaluating reflection and absorption coefficients with this approximation is presented. The evaluation of the absorption coefficient at normal incidence is performed on a porous layer on a rigid backing, and compared to measurements performed using a two microphone technique and an impedance tube.
Wave Motion | 2002
Jean François Allard; Gert Jansens; Walter Lauriks
Expressions for the spherical acoustic field reflected by a porous or a fluid layer of finite thickness having a surface impedance noticeably dependent on the angle of incidence are obtained using the classical steepest descent path and the pole subtraction method. The domains of validity of both methods are defined. A simple expression that is valid for the case of thin layers, where the one intrinsic parameter is the surface impedance at grazing incidence, is obtained using the pole subtraction method.
Acta Acustica United With Acustica | 2003
Jean François Allard; Gareton; Michel Henry; Gert Jansens; Walter Lauriks
Acta Acustica United With Acustica | 2004
Laurens Boeckx; Gert Jansens; Walter Lauriks; Dg Albert
Proc. Building Simulation '99 | 1999
Marinus van der Voorden; Lau Nijs; Gerrit Vermeir; Gert Jansens
Proceedings of the Institute of Acoustics | 2003
Laurens Boeckx; Gert Jansens; Walter Lauriks; Gerrit Vermeir
Proceedings Research Symposium "Acoustic Characteristics of Surfaces" | 2003
Gert Jansens; Laurens Boeckx; Walter Lauriks; Jean François Allard
Proceedings of the Institute of Acoustics | 2003
Gert Jansens; Laurens Boeckx; Walter Lauriks; Jean François Allard