Photon correlation method for acoustic pressure measurement in free sound field

Microphones are calibrated by reciprocity method currently, but not for the nonstandard size microphones. To solve the calibration problem for nonstandard microphones, research on a non-invasive optical method for acoustic pressure measurement in free sound field. By auto-correlating scattered photon sequences, the particle velocity can be measured, and further acquiring the acoustic pressure at certain position. Experiment results show , the difference between photon correlation method and standard microphone is within 0.61 dB when the acoustic frenquency is between 200Hz and 8kHz, verifying the feasibility of the correlation method.