Abstract: A phased microphone array capable of being placed in the free stream flow of a wind tunnel test section. The array consists of a plane of microphones on arms radiating out from a central hub. Microphones are placed along the length of the arms. The array is to be fastened to an articulated mount which allows it to be repositioned and be placed in a number of viewing positions. The ideal arms are symmetric airfoils that rotate about the longitudinal axis of the arm so that in free flow the airfoils point into the oncoming flow. Microphones placed at the leading edge will be located at stagnation points decreasing wind turbulence and boundary layer effects.

Abstract: A phased microphone imaging array and repeatable sound source are used in concert to determine absorption and reflection coefficients of materials and spaces across a continuous frequency domain. Coefficients can be determined at normal and oblique incidences to the surface using beamforming software. The invention can be used in-situ without needing to alter the environment in which it is testing. Accurate results can be obtained at any distance from the array and sound source to the testing surface with relatively little material.