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

Area of Science:

• Acoustics and Signal Processing
• Metrology and Calibration

Background:

• Accurate calibration of infrasonic acoustic sensors (DC to several Hz) is crucial for detecting, localizing, and characterizing infrasonic events.
• Established calibration techniques face challenges in the low-frequency infrasound range, leading to increased uncertainty when using traditional microphone references.
• Existing methods struggle to provide traceable calibrations with low uncertainty below a few hertz.

Purpose of the Study:

• To develop a reliable reference acoustic sensor for comparison-calibration of infrasonic transducers and arrays.
• To establish a method for bridging the DC to tens of hertz frequency range with low uncertainty.
• To enable laboratories without primary calibration capabilities to perform traceable calibrations.

Main Methods:

• Utilized a barometric sensor, known for its response at zero frequency, as a comparison-calibration reference.
• Developed a low-pass model for the complex frequency response of the barometric reference sensor.
• Focused on preserving the low uncertainty of the barometric reference across the target frequency range.

Main Results:

• Successfully modeled the barometric sensor's frequency response from DC to tens of hertz.
• Demonstrated the feasibility of using a barometric sensor as a low-uncertainty reference for infrasound calibration.
• Achieved traceable comparison calibrations in the hundredths to tens of hertz region.

Conclusions:

• A barometric sensor, when modeled appropriately, serves as an effective reference for low-frequency acoustic calibration.
• This method significantly reduces calibration uncertainty in the challenging infrasound range.
• The approach democratizes access to accurate infrasound calibration for a wider range of laboratories.