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Response Identification in the Extremely Low Frequency Region of an Electret Condenser Microphone
Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, 70701, Taiwan
* Author to whom correspondence should be addressed.
Received: 11 November 2010; in revised form: 20 December 2010 / Accepted: 27 December 2010 / Published: 10 January 2011
Abstract: This study shows that a small electret condenser microphone connected to a notebook or a personal computer (PC) has a prominent response in the extremely low frequency region in a specific environment. It confines most acoustic waves within a tiny air cell as follows. The air cell is constructed by drilling a small hole in a digital versatile disk (DVD) plate. A small speaker and an electret condenser microphone are attached to the two sides of the hole. Thus, the acoustic energy emitted by the speaker and reaching the microphone is strong enough to actuate the diaphragm of the latter. The experiments showed that, once small air leakages are allowed on the margin of the speaker, the microphone captured the signal in the range of 0.5 to 20 Hz. Moreover, by removing the plastic cover of the microphone and attaching the microphone head to the vibration surface, the low frequency signal can be effectively captured too. Two examples are included to show the convenience of applying the microphone to pick up the low frequency vibration information of practical systems.
Keywords: response identification; extremely low frequency; electret condenser microphone; time frequency analysis
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Cite This Article
MDPI and ACS Style
Jeng, Y.-N.; Yang, T.-M.; Lee, S.-Y. Response Identification in the Extremely Low Frequency Region of an Electret Condenser Microphone. Sensors 2011, 11, 623-637.
Jeng Y-N, Yang T-M, Lee S-Y. Response Identification in the Extremely Low Frequency Region of an Electret Condenser Microphone. Sensors. 2011; 11(1):623-637.
Jeng, Yih-Nen; Yang, Tzung-Ming; Lee, Shang-Yin. 2011. "Response Identification in the Extremely Low Frequency Region of an Electret Condenser Microphone." Sensors 11, no. 1: 623-637.