Calibration of pressure-velocity probes using a progressive plane wave reference field and comparison with nominal calibration filters

A procedure for calibrating pressure-velocity (p-v) sound intensity probes using a progressive plane
wave as reference field is presented here. The procedure has been checked for a microelectromechanical
system technology-based MicroflownVR match-size probe by comparing the calibration
results with the nominal correction curves available from the manufacturer. The reference field was
generated along a wave guide by means of a dual cone loudspeaker supplying acoustic energy in
the range 20 Hz-20 kHz through an impedance adaptor. Different from the current in-field procedures,
the one proposed here allows the calibration of probes under test to be executed at once up to
10 kHz without any change in the experimental setup. After a detailed review of the general principles
of calibration, the procedure has been finalized with three main stages: (a) determination of the
full coherence calibration bandwidth of the probe, (b) comparison calibration of the probe built-in
pressure microphone over the full coherence frequency range, and (c) relative calibration of the velocity
sensor over the calibrated pressure one. Calibration results for the probe under test have been
best fitted against the calibration filters modeled by the manufacturer and the direct comparison of
the obtained data with the factory ones has been reported.