An improvement method of the speech quality by pitch compensation in transition region in G.723.1

G.723.1 uses pitch and gain coefficient for periodicity of speech and LSP (line spectrum pairs) coefficient for spectrum. However, this encoder processes without considering difference between stable and unstable speech region, especially transient region. Therefore, it is impossible to detect exact pitch in transition region. So, speech degradation is produced. In this paper, we propose the new algorithm that improves speech quality in G.723.1 by detecting exact pitch in transition region. First of all, we decide threshold of pitch gain coefficient in stable region by using pitch gain coefficient from G.723.1. If pitch gain coefficients exceed threshold value, pitch gain coefficient is recalculated by controlling before and after 10 sample. And then pitch gain coefficient close to the threshold value is determined. After this processing, pitch and pitch gain coefficient are coded.