| 摘要 |
PURPOSE:To perform voice speech smoothly by controlling the sound volume of a speaker in reception voice corresponding to an ambient noise in a vehicle, and decreasing a gain when only a noise exists in transmission voice and increasing the gain when voice exists in it. CONSTITUTION:The extraction of a noise level and that of a voice signal are performed from the voice signal in which a noise signal is mixed inputted from a mike 1, and S/N output is found. Meanwhile, unstationary voice output is obtained by passing a mix signal through a level differentiation circuit in a voice level detection control circuit 33, and the gain of a mike signal amplifier 34 is controlled by a value in which the voice output is multiplied by the S/N output. A noise level detection control circuit 31 obtains the noise level as the output of the level integrating circuit, and the gain of a speaker driving amplifier 32 is controlled by the output, and the voice of the speaker is increased when the noise is increased. As for the transmission voice, since the gain of the mike signal amplifier is increased at the time of the voice is detected, it is possible to perform the speech of the voice smoothly. |
