INFORMATION PROCESSING APPARATUS AND METHOD, AND RECORDING MEDIUM

In order to improve the accuracy of an excitation source for a band-spreading apparatus and to generate a wide-band signal having no gaps, an &agr; band-widening section generates a prediction coefficient &agr;W of a wide-band speech signal from a prediction coefficient &agr;N of a narrow-band speech signal. An oversampling apparatus oversamples a narrow-band speech signal sndN. An interpolation section generates an adaptive signal excPW of a wide-band speech signal from an adaptive signal excPN of the narrow-band speech signal. A zero-filling section generates a noise signal of a wide-band speech signal from a noise signal excNN of the narrow-band speech signal. A noise addition section adds a noise signal which is a gap of the wide-band speech signal and generates a noise signal excNW. An adder generates an excitation source excPW for the wide-band speech signal from the adaptive signal excPW and the noise signal excNW of the wide-band speech signal. A wide-band LPC combining section generates a wide-band speech signal. A band suppression section suppresses a frequency band contained in the narrow-band speech signal within the wide-band speech signal. An adder outputs a wide-band speech signal sndW from the wide-band speech signal and the oversampled narrow-band speech signal.