Source Height Determination for Several Sources at the Same Height

Equivalent acoustic source height is an important parameter for accurate predictions of the acoustic impact of transportation infrastructures. Research has shown that this parameter can be obtained from a two-microphone technique in the case of one broadband omnidirectional point source above an homogeneous ground, modeled as a Delany-Bazley absorber. It is shown in this paper that this method can be generalized to n broadband sources with same height, above an homogeneous ground or a ground with an impedance discontinuity. All sources are considered to have the same emission spectrum. The method is based on the comparison of the level difference spectrum between two microphones - hereinafter called attenuation spectrum - measured and computed. Numerical and experimental validations confirm the reliability of the method for controlled noise sources. Furthermore, it is demonstrated that qualitative assessment of ground parameters is sufficient to obtain an accurate source height determination.