Patent ID: 7684979

Claim:
A band extending apparatus comprising: a spectral parameter calculating unit, receiving at least an input signal of a preset frequency band to calculate spectral parameters representing spectral characteristics; a noise generating unit for generating a noise signal; a coefficient calculating unit for shifting the frequency of said spectral parameters to then find filter coefficients; a gain unit for supplying a gain to an output of said noise generating unit; a synthesis filter unit for passing an output signal of said gain unit through a synthesis filter, formed using said filter coefficients, to reproduce a signal for band extension; means for adding a signal corresponding to said input signal converted in a sampling frequency thereof to an output signal of said synthesis filter unit to generate a band extended signal; and a voiced/unvoiced discriminating circuit, receiving said input signal of the preset frequency band, to verify whether the input signal in terms of a frame as a unit is voiced or unvoiced; wherein said gain unit includes: a gain adjustment unit, receiving voiced/unvoiced discrimination information output from said voiced/unvoiced discriminating circuit, to adjust the gain to be imparted to the output signal of said noise generating circuit, depending on whether said voiced/unvoiced discrimination information indicates voiced or unvoiced; and a gain circuit, receiving said gain adjusted by said gain adjustment unit to multiply the output signal of said noise generating unit with said gain to output the resulting signal.