Super directive spectrum analyzer by use of moving microphones

This paper describes a new method of estimating spectrum of incident sound from a specified direction. A fixed microphone and a moving microphone form a basic composition. The moving microphone moves along a straight line from the fixed one to the specified direction. After giving the time delay to the output of the moving microphone according to the distance between two microphones,the cross spectrum and the coherence function are computed from the outputs of these microphones. The longer the span of the moving microphone, the sharper the directivity is. The beam is arbitrarily directed by adjusting phase in the case of three or more moving microphones.