A reference for ear-canal absorbance based on semi-anechoic waveguides.

Area of Science:

• Audiology
• Acoustics
• Biomedical Engineering

Background:

• Wideband acoustic immittance (WAI) is crucial for assessing middle-ear function and diagnosing conductive hearing loss.
• Current clinical adoption of WAI is limited due to a lack of measurement accuracy evidence and international standards.
• A key challenge for standardization is the absence of a defined acoustic load reference mimicking the adult ear canal.

Purpose of the Study:

• To explore and propose methods for establishing an acoustic load reference for WAI measurements.
• To quantify the measurement accuracy of WAI instrumentation.
• To lay the groundwork for future international standards in WAI measurement.

Main Methods:

• Investigated standardized occluded-ear simulators as potential acoustic load references.
• Developed and tested semi-anechoic waveguides with varying cross-sectional area discontinuities.
• Proposed a method using an occluded-ear simulator for monitoring WAI calibration stability over time.

Main Results:

• Ear simulators and specialized waveguides offer viable approaches for creating known acoustic loads.
• These methods can be used to quantify WAI measurement accuracy.
• A stable calibration monitoring method using an ear simulator was demonstrated.

Conclusions:

• Standardized acoustic loads are essential for ensuring the accuracy and reliability of WAI measurements.
• Semi-anechoic waveguides represent a promising avenue for future WAI standardization.
• The proposed calibration monitoring technique can enhance the long-term stability of WAI instruments.