Patent ID: 8787585

Claim:
A matrix decoding method for decoding N audio input signals to determine M audio output signals, where M and N are integers and M is greater than N, and N=2, said method including the steps of: transforming ( 10 , 11 ) the N audio input signals from the time domain into the frequency domain to generate N streams of input frequency components; determining power ratios ( 17 , 30 , 31 , 32 , 33 ) from the streams of input frequency components, said power ratios including at least one power ratio for each critical frequency band in a set of critical frequency bands, wherein the set of critical frequency bands is determined in accordance with perceptually motivated considerations; determining gain control values ( 17 , 38 ) for each of the critical frequency bands from the power ratios including by shaping the power ratios in a nonlinear fashion, wherein the shaping of the power ratios in nonlinear fashion includes a step of exponentiating at least one value determined from at least one of the power ratios with an exponent at least substantially equal to three; operating an active matrix subsystem ( 16 ) to generate M streams of output frequency components in response to the streams of input frequency components; wherein the active matrix subsystem ( 16 ) is steered using the gain control values; wherein the active matrix subsystem ( 16 ) applies multiple sets of matrix coefficients to the streams of input frequency components, each set of matrix coefficients for a different one of the critical frequency bands; and transforming ( 20 ) the streams of output frequency components from the frequency domain into the time domain, thereby generating the M audio output signals.