Patent ID: 7650000

Claim:
An audio device which produces surround signals of a plurality of channels on the basis of audio signals of two channels constituting input signals, characterized in that this audio device is provided with: a correlation eliminating filter whereby the input signal of a first channel is divided by a multi-stage delay processing device, a specified filter coefficient is superimposed by a coefficient processing device for each of the divided multi-stage outputs so that multi-stage output components are produced, and signal components that have a high correlation with the input signal of a second channel are extracted from the input signal components of the first channel by adding these multi-stage output components; and an adaptive correlation eliminating device comprising a coefficient updating processing device which constantly varies the characteristics of the correlation eliminating filter on the basis of error signals obtained by means of the output signals and the input signals from the second channel, the input signals from the first channel, and a step size parameter which controls an updating speed of the specified filter coefficient, and the difference between the output from the correlation eliminating filter and the input signals from the second channel is calculated and output as a surround signal.