| 摘要 |
PURPOSE:To eliminate the residual noise dependent upon the saturation level by storing private voice in the relationship between the level of synthetic voice, where synthetic voice from plural telephone sets and private voice are synthesized, and the saturation level of an A/D converter. CONSTITUTION:In the control circuit, private voice to be output currently is added to synthetic voice of received two or more persons in 5, and private voice with synthetic voice added is stored in 3. Next, private voice is subtracted from synthetic voice of received three or more persons including private voice in 2, and private voice to be output currently is added to the subtraction result in 5. At a voice transmission time, when synthetic voice of three or more persons including private voice exceeds the amplitude saturation level of an A/D converter, voice equal to the saturation level is transmitted, and then, the difference quantity between voice of the saturation level and synthetic voice including no private voice is stored, and this quantity is subtracted from voice of the saturation level received next. |
