| 摘要 |
PURPOSE:To realize VOX control which reduces speak start cutting or malfunction under high noises. CONSTITUTION:The difference between the average power of a silence frame and input power, namely, a change amount is calculated by a voice detector at a step ST 2-1. A threshold value 1 is calculated in inverse proportion to the average power of the silence frame at a step ST 2-2. When the change amount is smaller than this threshold value 1 and the absolute value of a first- order reflection coefficient r1 is smaller than a threshold value 2, it is judged that a present frame is the silence frame (steps ST 2-3 and ST 2-4). When it is judged as the silence frame, the weighted average value of the average power of the present silence frame and the power of the present frame is defined as the average power of the new silence frame at a step ST 2-5. Since the average power of the silence frame to be a judgement reference is updated, the suitable VOX control adaptive to the level of the noise or the like is provided. |
