A New Method for Airborne Sound Detection Using Total Internal Reflection and Its Application to MicrophoneReport as inadecuate

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Advances in Optical TechnologiesVolume 2011 2011, Article ID 547597, 9 pages

Research Article

Department of Electronic Media Technology, Gunma National College of Technology, 580 Toriba-cho, Maebashi 371-8530, Japan

Tohoku University, 543-1-504 Niiharu-cho, Midori-ku, Yokohama 226-0017, Japan

Received 2 August 2011; Accepted 24 August 2011

Academic Editor: Saulius Juodkazis

Copyright © 2011 Yasushi Suzuki and Ken-iti Kido. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A new method for detecting the sound pressure in air, which uses the total internal reflection at the curved interface between glass and air, is proposed, and its application to microphone is discussed. The critical angle for total reflection changes by the refractive index of air, which depends on the air density. The density changes by the sound pressure. Therefore, the sound pressure is measurable by detecting the intensity of the reflected light from the total reflection area. The sound pressure sensitivity of the proposed method is investigated theoretically and experimentally. Experimental results show that the microphone using the method is feasible though its sensitivity is low in the present stage. When the sensitivity is improved dramatically for practical use, the microphone becomes very sensitive to the surrounding conditions. A method to compensate the fluctuation of atmospheric pressure or temperature is presented.

Author: Yasushi Suzuki and Ken-iti Kido

Source: https://www.hindawi.com/


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