Sound encoding method and sound decoding method, and sound encoding device and sound decoding device

摘要

A high quality speech is reproduced with a small data amount in speech coding and decoding for performing compression coding and decoding of a speech signal to a digital signal. In speech decoding method according to a code-excited linear prediction (CELP) speech, a noise level of a speech in a concerning decoding period is evaluated by using a decoded gain of the speech based on a gain code included in the coded speech.