Active Noise Control by a Beam-Steerable Parametric Speaker with a Human Tracking System Equipped with a Motion Sensor

Parametric speakers have attracted considerable attention in the sound industry owing to their sharp directivity. Some investigations have reported active noise control using such speakers wherein noise is reduced in a limited area without affecting the surrounding. However, the direction control of speakers is necessary, because the area in which the sound propagates is of a few tens of centimeters. Therefore, if the audience moves in an area of a few square meters, it becomes necessary to track the audience and control the sound direction. This study aims to develop an active noise control system with a human tracking system using a beam-steerable parametric speaker equipped with a motion sensor (Kinect, Microsoft Corp.), which is mounted on the parametric speaker. The motion of the audience was tracked by the sensor and position of the audience head was measured. The phase of the modulated signal applied to each transducer element is shifted using field-programmable gate arrays to direct the sound beam toward the head. The phase of the sound wave and sound pressure was also controlled. Active noise control by the speaker with a human tracking system has been successfully demonstrated.