| 摘要 |
PURPOSE:To eliminate a wind break noise component of a microphone without sound quality deterioration by providing a low pass filter controlling a high cut-off frequency with an output of a low frequency component intensity detection circuit to the sound circuit. CONSTITUTION:An output signal V1 of a microphone 1 is amplified by a variable gain amplifier 2 and outputted through an HPF (high pass filter) 3 and an LPF (low pass filter) 4. On the other hand, a low frequency component (LF component) being a wind break noise component of the microphone signal V1 is detected by an LF level detection circuit 5, which converts the component into DC signals V11 and V12, they are applied respectively to the HPF 3 and the LPF 4, whose cutoff frequency is changed. For example, when a wind break noise sound is large, the signal V11 is increased to control the HPF 3 and the LPF 4 thereby increasing the cut-off frequency of the HPF 3 and decreasing the cut-off frequency of the LPF 4. Conversely when the wind break noise sound is small, the signal V11 is decreased to control the HPF 3 and the LPF 4 thereby decreasing the cut-off frequency of the HPF 3 and increasing the cut-off frequency of the LPF 4 and widening a band width of an output signal V2. |
