BEAMFORMING METHOD USING ONLINE LIKELIHOOD MAXIMIZATION COMBINED WITH STEERING VECTOR ESTIMATION FOR ROBUST SPEECH RECOGNITION, AND APPARATUS THEREFOR

A target signal extraction apparatus according to an embodiment of the present invention may comprise a steering vector estimator and a beamformer. The steering vector estimator may generate an input signal covariance according to input results for each frequency over time, generate a noise covariance on the basis of a variance determined according to output results corresponding to the input results, and generate a steering vector on the basis of the input signal covariance and the noise covariance. The beamformer may generate a beamforming weight according to a beamforming covariance determined according to the variance and the steering vector, and provide the output results on the basis of the input results and the beamforming weight. The target signal extraction apparatus according to the present invention may generate the steering vector by calculating the noise covariance on the basis of the variance determined according to output results corresponding to input results, and increases extraction performance for a target sound source by updating a beamforming weight.