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.
Highlights
Because of the rapid development of web sites and computer software and hardware, peripheral devices from electret condenser microphones [1,2,3] to webcams to printers are becoming more and Sensors 2011, 11 more popular
By properly equipping one with suitable software, it can pick up dominant vibration information from a system in operation to serve as a type of non-contact warning equipment
An integrated circuit involving the field effect transistor will amplify the signal induced by the capacity’s change. These facilities and personal computer (PC) board are enclosed by a capsule
Summary
Because of the rapid development of web sites and computer software and hardware, peripheral devices from electret condenser microphones [1,2,3] to webcams to printers are becoming more and Sensors 2011, 11 more popular. Since they are all produced on a mass scale, they are often very cheap yet still of high quality. By properly equipping one with suitable software, it can pick up dominant vibration information from a system in operation to serve as a type of non-contact warning equipment. In [8], we applied it to pick up the arterial pulse pressure information of human wrist vessels, suggesting the potential for constructing a diagnosis system
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
