Real-time acoustic blind signal separation system based on the spatio-temporal gradient analysis

This paper presents an autonomous directivity microphone system for the blind source separation based on the newly proposed spatio-temporal gradient algorithm. The blind source separation technique principally uses no a priori knowledge about parameters of convolution, filtering, nor mixing. In the simplest case of the blind source separation problems, the observed mixing signals are the linear combinations of unknown source signals which are mutually and statistically independent and contain zero mean. The proposed blind signal separation algorithm utilizes the linearity among the four signals: (1) the sound pressure, (2) x, (3) y, and (4) z-directional particle velocities, all of which are governed by the wave equation and the equation of motion. The proposed method, therefore, has an ability to simplify the convoluted blind source separation problems into the instantaneous blind source separation problems over the spatio-temporal gradient space. Several acoustical experiments have been performed with acceptable performance of the proposed method of blind source separation. A sensor for measuring the particle velocity of acoustic signal has been used in the experiment.