11. A speech decoding apparatus having a decoder configured to: receive, by the decoder, a coded speech signal including a gain code; decode, by the decoder, a gain from the gain code; decode a time series vector based on the coded speech signal, the time series vector having a number of samples with zero-amplitude; modify the time series vector based on the decoded gain such that the number of samples with zero amplitude-value is changed; and synthesize a speech signal based on the modified time series vector.
11. A speech decoding apparatus having a decoder configured to: receive, by the decoder, a coded speech signal including a gain code; decode, by the decoder, a gain from the gain code; decode a time series vector based on the coded speech signal, the time series vector having a number of samples with zero-amplitude; modify the time series vector based on the decoded gain such that the number of samples with zero amplitude-value is changed; and synthesize a speech signal based on the modified time series vector. 12. The apparatus of claim 11 , further configured to: obtain an adaptive code vector from an adaptive codebook based on an adaptive code associated with the coded speech signal.