Method of filtering noise of source digital data

Abstract

A method of filtering digital audio data with short delay according to the present invention comprises the steps of: (a) buffering input source digital audio data; (b) calculating digital data that are being filtered from the buffered input source digital audio data; and (c) outputting a portion of the filtered digital data. The source digital audio data are sequence of digital samples. Buffer contents are shifted to arrange some of input samples in a buffer in the step (a). The step (b) comprises the steps of: (b-1) calculating a correlation matrix; (b-2) decomposing the correlation matrix; (b-3) calculating a filter matrix; and (b-4) calculating an approximation of the filtered digital data. In the step (b-2), the correlation matrix is represented by multiplication of three matrices where a first matrix is a matrix composed by normalized eigenvectors of the correlation matrix, a second matrix is a diagonal matrix in which eigenvalues of the correlation matrix are arranged on a principal diagonal and zeros are arranged in other positions, and a third matrix is a transposed matrix of the normalized eigenvectors of the correlation matrix.