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Optical-cavity-based primary sound standard



Akobuije Chijioke, Richard A. Allen, Steven E. Fick, David Long, Benjamin Reschovsky, Jared Strait, Randall P. Wagner


We propose an optical sound standard in which the sound pressure is directly measured by using an optical cavity to observe the induced change in the refractive index of air. In this method, an optical cavity is coupled with an acoustic cavity, with the device to be calibrated (e.g. a microphone) inserted into one wall of the acoustic cavity. We believe that the method can achieve low-uncertainty measurement of sound pressure in air from infrasonic (e.g. 0.1 Hz) to ultrasonic (e.g. 100 kHz) frequencies. At the lower frequencies a coupler configuration is suitable, in which the sound field is uniform in the acoustic cavity, while at higher frequencies a resonator configuration is suitable, in which a standing sound wave is maintained in the acoustic cavity. The method is also amenable to incorporation into inherently traceable optical microphones, which measure the local sound level by the change in the air refractive index. We have designed a system to measure sound and calibrate microphones at 1 kHz using an acoustic resonator. We are presently constructing this system and will report on experimental progress and our latest results.
Proceedings Title
28th International Congress on Sound and Vibration 2022 (ICSV28)
Conference Dates
July 24-28, 2022
Conference Location
Singapore, SG
Conference Title
ICSV28: 28th International Congress on Sound and Vibration


acoustic standard, optical cavity, primary standard, refractive index


Chijioke, A. , Allen, R. , Fick, S. , Long, D. , Reschovsky, B. , Strait, J. and Wagner, R. (2023), Optical-cavity-based primary sound standard, 28th International Congress on Sound and Vibration 2022 (ICSV28), Singapore, SG, [online], (Accessed May 24, 2024)


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Created February 1, 2023, Updated June 12, 2023