The barometric-pressure sensor as a comparison-calibration reference for acoustics from 0.01 to 10 hertz.

This article focuses on developing a method to use a barometric-pressure sensor with a well-characterized complex frequency response as a reference for comparison calibration of infrasound sensors in the challenging frequency range from near-zero (DC) to tens of hertz. Specifically, it demonstrates that the Setra 278 barometric-pressure sensor, which has a simple second-order low-pass frequency response model defined by two parameters—the DC response (S0) traceable to the National Institute of Standards and Technology (NIST) and a characteristic frequency (f0)—can serve as a low-uncertainty reference sensor for infrasonic calibration. The characteristic frequency f0 is determined by fitting the sensor's phase response against that of a calibrated infrasound microphone (e.g., Brüel & Kjær BK4193), and its uncertainty is estimated via Monte Carlo simulations based on the microphone's calibration uncertainties. The approach yields combined uncertainties in magnitude and phase for the Setra 278 that are lower than those of the infrasound microphone used for calibration, enabling laboratories without primary calibration capabilities to perform traceable secondary calibrations with uncertainties well below one percent in the 0.01 to 10 Hz frequency range.