Patent ID: 8073703

Claim:
An acoustic signal processing apparatus which converts down-mixed acoustic signals of NI channels to acoustic signals of NO channels, where NO>NI, using spatial information parameters updated for each of a plurality of frames separated by a predetermined time interval, said acoustic signal processing apparatus comprising: a processor; a first matrix arithmetic unit operable to perform, using said processor, matrix arithmetic for the down-mixed acoustic signals of the NI channels; K decorrelation units operable to, with respect to output signals of said first matrix arithmetic unit, generate signals which are incoherent, in terms of time characteristics, with the signals obtained after the matrix arithmetic performed by said first matrix arithmetic unit, while maintaining frequency characteristics of the signals obtained after the matrix arithmetic performed by said first matrix arithmetic unit; a second matrix arithmetic unit operable to (i) perform matrix arithmetic for output signals of said K decorrelation units and for the down-mixed acoustic signals of the NI-channels for which the matrix arithmetic has not been performed by said first matrix arithmetic unit and which have not been decorrelated by said K decorrelation units, and (ii) to output the acoustic signals of the NO channels; and a determinant generation unit operable to generate matrix coefficients of said first matrix arithmetic unit and matrix coefficients of said second matrix arithmetic unit, using the spatial information parameters, wherein said determinant generation unit is operable to generate a determinant for each of the plurality of frames so that (i) a first determinant of said first matrix arithmetic unit has K rows and NI columns and (ii) a second determinant of said second matrix arithmetic unit has NO rows and (NI+K) columns, wherein the first determinant with K rows and NI columns of said first matrix arithmetic unit is formed only by minimum-unit coefficients that are related to gain control and are necessary for said K decorrelation units, the minimum-unit coefficients being obtained by separating (i) coefficients that are related to the gain control and are necessary for said K decorrelation units from (ii) coefficients related to the gain control, and wherein the second determinant with NO rows and (NI+K) columns of said second matrix arithmetic unit is formed by coefficients which are obtained by combining (i) coefficients that are related to the gain control and are unnecessary for said K decorrelation units and (ii) coefficients related to phase control.