Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, 70701, Taiwan.
Sensors (Basel). 2011;11(1):623-37. doi: 10.3390/s110100623. Epub 2011 Jan 10.
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.
本研究表明，在特定环境下，与笔记本电脑或个人计算机（PC）相连的小型驻极体电容麦克风在极低频区域具有显著的响应。它将大部分声波限制在一个微小的空气腔内，如下所述。空气腔是通过在数字多功能光盘（DVD）盘上钻一个小孔来构建的。一个小扬声器和一个驻极体电容麦克风被安装在孔的两侧。因此，扬声器发出并到达麦克风的声能足以使后者的振膜振动。实验表明，一旦扬声器边缘允许有小的空气泄漏，麦克风就能捕捉到 0.5 到 20 Hz 范围内的信号。此外，通过去除麦克风的塑料外壳并将麦克风头连接到振动表面，也可以有效地捕捉低频信号。文中包含两个实例来说明该麦克风应用于获取实际系统低频振动信息的便利性。
