Patent ID: 7920711

Claim:
An audio device comprising: a first surround signal generation unit for receiving an L signal and an R signal as 2-channel stereo signals, extracting a component of the R signal having high correlation with the L signal, and subtracting the extracted component of the R signal from the L signal, thereby generating a first surround signal; and a second surround signal generation unit for extracting a component of the L signal having high correlation with the R signal, and subtracting the extracted component of the L signal from the R signal, thereby generating a second surround signal, wherein the first surround signal generation unit extracts the component of the R signal having high correlation with the L signal by updating a filter coefficient of a first adaptive filter using an adaptive algorithm; the second surround signal generation unit extracts the component of the L signal having high correlation with the R signal by updating a filter coefficient of a second adaptive filter using the adaptive algorithm; and plural sets of the first and second surround signal generation units are provided, and each of the plural sets has a different value of a step size parameter μ for use in updating the associated filter coefficient using the adaptive algorithm, so that each level of subtracting the associated component from the L signal or the R signal when the first and second surround signal is generated is differentiated there between, wherein the plural sets of the first and second surround signal generating units are connected to surround speakers for outputting the first or second surround signals, and wherein the value of the step size parameter μ corresponding to the surround speakers are set larger as farther the surround speakers are positioned from speakers for outputting each of the L signal and the R signal.