APPARATUS AND A METHOD FOR CODING AND DECODING VOICE WITH BIT RATE EXPANSION TO EXPAND A SIGNAL TO NOISE RATIO IN ORDER TO IMPROVE SOUND QUALITY

摘要

PURPOSE: An apparatus and a method for coding and decoding voice with bit rate expansion are provided to expand an SNR(Signal to Noise Ratio) in order to improve sound quality by including a fixed code book which forms multiple layers with a code book of an existing standardized voice codec. CONSTITUTION: A base layer(100) filters an input voice signal by using linear prediction coding and generates an excitation signal of the filtered voice signal based on fixed code book search and adaptive code book search. A speech enhancement layer(130) searches the fixed code book by using a parameter obtained by the fixed book search in the base layer. A multiplexer(140) multiplexes signals generated in the base layer and the speech enhancement layer and outputs a multiplexed signal.