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Physical Measurement Laboratory / Quantum Measurement Division

Mass and Force Group

Photonic Standards For Acoustics

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microphone diaphragm with laser spot and overlaid laser scan pattern
Image of microphone diaphragm with laser spot and overlaid laser scan pattern.
Credit: NIST
Experimental assembly for refractive index sound measurement
Experimental assembly for refractive index sound measurement.
Credit: NIST

This project seeks to advance the development and implementation of new, better, acoustical calibration methods based on optical sensing: (1) Use of laser Doppler vibrometer (LDV) measurements of microphone volume velocity to achieve improved reciprocity-derived secondary calibrations; (2) Use of optical measurements of refractive index change to measure sound pressure with a refractive index sound standard (RISS). The LDV system will improve the uncertainties and simplify the procedure for secondary microphone calibrations done at the standard frequencies of 250 Hz and 1 kHz, resulting in time and cost savings. The refractive index sound pressure measurement will provide an independent traceability path, is expected to allow calibration of a wider range of devices at a wider range of frequencies and can provide traceability to a quantum standard.

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Metrology and Force metrology

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Created March 6, 2025