| 摘要 |
PROBLEM TO BE SOLVED: To effectively reduce wind noise, solve problems that original signals, such as voice, are degraded caused by large wind noise and an SN ratio is decreased, and automatically achieve the same effects as a microphone using method which uses a proximity effect. SOLUTION: A signal processing circuit 12 at least amplifies output signals from a filter circuit 11 which performs high-pass filtering signals from a microphone 2. The filter circuit 11 has sequentially-connected six-step element circuits N1 to N6, and each step of the element circuits N1 to N6 is composed of a CR filter. The sixth element circuit N6 includes a transistor Tr1 as a variable resistance means. When the amplitude of an output signal from the signal processing circuit 12 increases, a resistance control circuit 13 changes a resistance value of the transistor Tr1 so that a cut-off frequency of the filter circuit 12 increases with decreasing of the amplitude of the output signal from the filter circuit 11. COPYRIGHT: (C)2008,JPO&INPIT
|
