Patent ID: 11956601
Assignee: GOVERNMENT OF THE UNITED STATES OF AMERICA, AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 13:
14. A process for comparison calibrating a test microphone, the process comprising:
disposing a reference microphone on a preamplifier-controller, the reference microphone comprising a reference microphone diaphragm;
producing an interferometer measurement light by an interferometer;
subjecting the reference microphone diaphragm of the reference microphone to the interferometer measurement light by aligning the interferometer measurement light to a first sampling location on the reference microphone diaphragm;
subjecting the reference microphone to an electrical waveform from the preamplifier-controller;
moving the reference microphone diaphragm according to the electrical waveform;
producing, by the reference microphone diaphragm, an acoustic wave comprising an amplitude and frequency from the electrical waveform;
determining, by the microphone driver, the drive current through the reference microphone;
producing, by the reference microphone diaphragm, interferometer backscattered light in response to the subjecting the reference microphone diaphragm to the interferometer measurement light;
receiving the interferometer backscattered light by the interferometer from the reference microphone diaphragm;
determining, by the interferometer, the motion of the reference microphone diaphragm from the interferometer backscattered light;
repositioning the interferometer measurement light to a different sampling location on the reference microphone diaphragm;
determining, by the interferometer, the motion of the reference microphone diaphragm at the different sampling location on the reference microphone from the interferometer backscattered light;
terminating the electrical waveform subjected to the reference microphone;
determining the pressure sensitivity of the reference microphone from the determinations of the motion of the test microphone diaphragm;
removing the reference microphone from the preamplifier-controller and disposing a test microphone on the preamplifier-controller, the test microphone comprising a test microphone diaphragm;
performing with the test microphone the following steps:
subjecting the test microphone diaphragm of the test microphone to the interferometer measurement light by aligning the interferometer measurement light to the first sampling location on the test microphone diaphragm;
subjecting the test microphone to the electrical waveform from the preamplifier-controller;
moving the test microphone diaphragm according to the electrical waveform;
producing, by the test microphone diaphragm, another acoustic wave comprising the amplitude and frequency from the electrical waveform;
determining, by the microphone driver, the drive current through the test microphone;
producing, by the test microphone diaphragm, interferometer backscattered light in response to the subjecting the test microphone diaphragm to the interferometer measurement light;
receiving the interferometer backscattered light by the interferometer from the test microphone diaphragm;
determining, by the interferometer, the motion of the test microphone diaphragm from the interferometer backscattered light from the test microphone diaphragm;
repositioning the interferometer measurement light to a different sampling location on the test microphone diaphragm; and
determining, by the interferometer, the motion of the test microphone diaphragm at the different sampling location on the test microphone from the interferometer backscattered light; and
terminating the electrical waveform subjected to the test microphone; and

determining the pressure sensitivity of the test microphone based on determinations of the motion of the test microphone diaphragm, the drive current of the test microphone, and the pressure sensitivity of the reference microphone.