Study of Frequency Response Characteristics in Sound measurment System Used by Optical Sensor
Keong-Tae Yeom, Kwan-Kyu Kim, Hwa-Young Choi, Byeong-Man Kwon, Yong-Kab Kim · 2008
This paper, in order to analyze property of frequency response in Sound measurment system using optical sensor, system was implemented. The capacitance microphone and fiber-optic transmission path type fiberoptic microphone (FOM) have weaknesses in directivity, size, weight, and price. However suggested optical microphone can be constituted by cheap devices, so it has many benefits like small size, light weight, high directivity, etc. Head part of optical microphone which is suggested in this paper is movable back and forth by sound pressure with the attached reflection plate. Operating point is determined by measuring the respond characteristics and choosing the point on which has maximum linearity and sensitivity while changing the distance between optical head and vibrating plate. We measured the output of the O/E transformed signal of the optical microphone while frequency of sound signal is changed using sound measuremnet/analysis program, Smaart Live and USBPre, which are based on PC, and compared the result from an existing capacitance microphone. The measured Optical microphone showed almost similar output characteristics as those of the compared condenser microphone, and its bandwidth performance was about 3㎑ at up to 5 ㏈.