WIDE-BAND SPEECH CODING SYSTEM, WIDE-BAND SPEECH DECODING SYSTEM, HIGH-BAND SPEECH CODING AND DECODING APPARATUS AND ITS METHOD

PROBLEM TO BE SOLVED: To provide a high-band speech coding apparatus and a decoding apparatus in which high quality sound can be reproduced even at a low bit rate. SOLUTION: A high-band speech coding apparatus 202 includes: a first coding unit 308 which encodes a high-band speech signal based on a structure in which a harmonic structure and a stochastic structure are combined, if the high-band speech signal has a harmonic component; and a second coding unit 309 which encodes a high-band speech signal based on a stochastic structure if the high-band speech signal has no harmonic components. The high-band speech decoding apparatus includes: a first decoding unit which decodes a high-band speech signal based on a combination of a harmonic structure and a stochastic structure using received first decoding information; a second decoding unit which decodes the high-band speech signal based on a stochastic structure using received second decoding information; and a switch outputting one of the decoded high-band speech signals received from the first and second decoding units according to received mode selection information. COPYRIGHT: (C)2006,JPO&NCIPI