Speech decoding apparatus, speech decoding method, and audio decoding program

PROBLEM TO BE SOLVED: To improve the subjective quality of a decoded signal by reducing generated pre-echoes and post-echoes without significantly increasing a bit rate in a band extension technology in a frequency region represented by SBR. SOLUTION: A voice decoding device obtains a linear prediction coefficient by performing linear prediction analysis in a frequency direction to a signal represented by the frequency region based on a covariance method or an autocorrelation method, and deforms a time envelope of the signal by adjusting a filter intensity for the obtained linear prediction coefficient and then by filtering the signal in the frequency direction based on the adjusted coefficient. COPYRIGHT: (C)2012,JPO&INPIT