A reciprocity method for validating acoustic ear-probe source calibrations.

Area of Science:

• Acoustics
• Biomedical Engineering
• Metrology

Background:

• Wideband acoustic immittance (WAI) measurements require precise ear probe calibration for accurate acoustic source parameter determination.
• Clinical applications of WAI are increasing, yet a lack of international standards compromises measurement reliability.
• Existing calibration methods for ear probes may contain undetected errors impacting WAI results.

Purpose of the Study:

• To introduce and validate a reciprocity method for evaluating the accuracy of ear probe source calibrations.
• To identify and quantify errors in ear probe calibrations that could lead to inaccuracies in WAI measurements.
• To assess the potential of this method for conformance testing in the development of future WAI standards.

Main Methods:

• A reciprocity calibration method was developed using two calibrated WAI instruments.
• Ear probes were positioned face-to-face within a short waveguide, allowing mutual measurement of acoustic source parameters.
• Direct comparison of calibrated and measured source parameters identified discrepancies indicative of calibration errors.

Main Results:

• The reciprocity method successfully identified previously undetected errors in exemplary ear probe calibrations.
• These identified errors were shown to influence WAI measurements in simulated and real ear scenarios.
• The method demonstrated high accuracy in detecting calibration inaccuracies.

Conclusions:

• The described reciprocity method is effective for verifying ear probe calibration accuracy in WAI measurements.
• This technique can significantly improve the reliability of WAI hardware and methods.
• While not suitable for routine calibration, it is valuable for conformance testing and future standardization efforts.