Directional measurement of airborne sound transmission paths using a spherical microphone array

A spherical microphone array has been used to perform directional measurements of airborne sound transmission between rooms. With a source and an array on opposite sides of a wall, omnidirectional impulse responses were measured to each of the array microphones. Beamforming resulted in a set of directional impulse responses, which were analyzed to find the distribution of arriving sound energy at the array position during various time ranges. Weak spots in the separating wall are indicated as directions of increased arriving sound energy. The system was able to identify minor defects in a test wall between two reverberation chambers, and also to identify leaks in the wall of an actual meeting room.