Classification of aircraft flight paths by detecting temporal changes in sound arrival direction

Automatic classification of flight paths related to observed aircraft noises is useful for unattended aircraft noise monitoring. This paper describes a method of detecting flight paths based on temporal changes in sound arrival direction. The method applies the acoustical cross-correlation technique using four microphones. The sound arrival direction is expressed as a set of unit vectors on the surface of a unit sphere assumed to be at the center of the microphones. A field experiment was carried out near an end of a runway to confirm the effectiveness of the procedure. The rate of correct classification was 93%.