Abstract
The low frequency phase characteristics of microphones in a monitoring system are crucial for characterizing large-scale natural and artificial activities—e.g., earthquakes, nuclear explosions, or rocket launchings. At present, microphones are simultaneously calibrated using in-situ or calibrator methods to get their phase consistency. However, the essential primary calibration, which traces their phase sensitivity to basic physical quantities, is grossly overlooked. Recently, we speculated that the microphone phase sensitivity is acoustically controlled by the pressure leakage and heat conduction effects in its back chamber, which will vary at low frequencies. Therefore, by means of the FEA (Finite Element Analysis) technique, simulations of laser pistonphone-based primary microphone calibrations are conducted both in the frequency and time domains. The frequency domain simulation quantifies the phase variation, while the time domain analysis helps us to understand the variation mechanism. It is found that the low frequency phase sensitivity is greatly influenced by its geometries and the venting state and should be pre-calibrated before serving.
Highlights
In the areas of sound source localization, photo-acoustic imaging, and sound intensity measurement, the phase characteristics of microphones are as important as their modulus characteristics [1,2,3,4]
The phase difference between the calibrating sound pressure and the piston displacement is the desired phase response of the pistonphone, as given in Figure 5, whose angle is calculated from dividing their phase response of the pistonphone, as given in Figure 5, whose angle is calculated from dividing their time time difference by by thethe calibration by360
The low frequency phase characteristics of microphones are crucial for large-scale natural and Theactivity low frequency phase characteristics of microphones are crucial for large-scale natural and artificial measurements, but their primary calibrations have been grossly overlooked
Summary
In the areas of sound source localization, photo-acoustic imaging, and sound intensity measurement, the phase characteristics of microphones are as important as their modulus characteristics [1,2,3,4]. The phase sensitivities thephase microphone whenof itsthe vent is connected to the sound field or calibrating sound field or the outside atmosphere are obtained based on a proposed joint simulation the outside atmosphere are obtained based on a proposed joint simulation method.
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