Monaural sound-source-direction estimation using the acoustic transfer function of an active microphone

This paper introduces an active microphone concept that achieves a good combination of active-operation and signal processing, where a new sound-source-direction estimation method using only a single microphone with a parabolic reflection board is proposed. A simple signal-power-based method using a parabolic antenna has been proposed in the radar field. But the signal-power-based method is not effective for finding the direction of a talking person due to the varying power of the uttered speech signals. In this paper, the sound-source-direction estimation method focuses on the acoustic transfer function instead of the signal power. The use of the parabolic reflection board leads to a difference in the acoustic transfer functions of the target direction and the non-target directions, where the active microphone rotates and observes the speech at each angle. The acoustic transfer function is estimated from the observed speech using the statistics of clean speech signals. Its effectiveness is confirmed by monaural sound-source-direction estimation experiments in a room environment.