Very near field of a dipole source above the impedance plane

A theoretical background for a new technique intended for in-situ measuring of sound absorption is presented. The measurement technique is a refinement of the classical method using reflection over the impedance plane. Refinement is based on the directivity pattern of dipole source in a very near field. Theoretical analysis of acoustical setup is based on the Rayleigh integral, which is used for calculations of sound propagation from complex sources. Analytical results with numerical simulations based on FEM analysis are compared in this preliminary study. Influence of flow resistivity on the sound pressure around a dipole source positioned over the impedance plane is investigated. Theoretical results provide an excellent starting point for the design platform of the new sensor for sound absorption.