| 摘要 |
PURPOSE:To obtain a broad and sharp directivity, by providing an acoustic resistive member so as to cover at least one side of a plurality of microphone units accommodated in a pipe frame having a net at both ends. CONSTITUTION:The 1st and 2nd microphones 1, 2 are inserted at both ends of a cylinder 11 for linking and the 3rd microphone 3 is inserted to one end of a cylinder 10. A microphone unit accommodated in the cylinders 10, 11 is accommodated to both ends of a square pipe frame 14 coaxially. The cylinder frame 14 has nets 4-9 at both ends, and the center is provided with a space 12 accommodating a circuit section such as an amplifier amplifying an output from the microphones 1-3 and a filter. Acoustic resistive members 15, 16 are arranged in the pipe frame 14 so as to be located at both ends of the space 12. In arranging the members 15, 16 like this, the peak around 2kHz can be attenuated for the directivity of 90 deg., allowing to obtain broad band. |
