Patent ID: 6829360
Filing Date: 2004-12-07
Classification: G10L

Abstract:
A method for expanding a band of an audio signal comprising:oversampling a digital audio signal of a first band having a predetermined maximum frequency with a sampling frequency that is two or more times the maximum frequency to produce an oversampled digital audio signal, and low-pass-filtering the oversampled digital audio signal so as to eliminate aliasing noise caused by the oversampling, and outputting the low-pass-filtered oversampled digital audio signal; calculating a spectrum intensity of a predetermined band of the low-pass-filtered oversampled digital audio signal, and outputting a signal indicating the calculated spectrum intensity; generating an expanded signal having frequency components of a second band higher than the first band; controlling a level of the expanded signal in response to the signal indicating the calculated spectrum intensity; and adding the expanded signal having the controlled level to the low-pass-filtered oversampled digital audio signal to produce an addition resultant digital audio signal, wherein said generating the expanded signal comprises: distorting the digital audio signal by performing nonlinear processing on the low-pass-filtered oversampled digital audio signal with a non-linear input and output characteristic, and generating a digital signal having higher harmonic components of the digital audio signal; and high-pass-filtering at least frequency components equal to or higher than the second band, from the digital signal having the higher harmonic components to produce a high-pass-filtered signal, and outputting the high-pass-filtered signal as the expanded signal.