Extended bandwidth real-ear measurement accuracy and repeatability to 10 kHz

Abstract

Objective: Direct real-ear measurement to the 4–6 kHz range can be measured with suitable accuracy and repeatability. This study evaluates extended bandwidth measurement accuracy and repeatability using narrowband and wideband signal analysis. Design: White noise was measured in female ear canals at four insertion depths using one-third and one-twenty-fourth octave band averaging. Study sample: Fourteen female adults with reported normal hearing and middle-ear function participated in the study. Results: Test-retest differences were within ±2 dB for typical frequency bandwidths at insertion depths administered in clinical practice, and for up to 8 kHz at the experimental 30 mm insertion depth. The 28 mm insertion depth was the best predictor of ear canal levels measured at the 30 mm insertion depth. There was no effect of signal analysis bandwidth on accuracy or repeatability. Conclusions: Clinically feasible 28 mm probe tube insertions reliably measured up to 8 kHz and predicted intensities up to 10 kHz measured at the 30 mm insertion depth more accurately than did shallower insertion depths. Signal analysis bandwidth may not be an important clinical issue at least for one-third and one-twenty-fourth octave band analyses.

Key Words:

• Assistive technology
• hearing aids
• hearing-aid satisfaction
• instrumentation

Acknowledgements

This work was supported by the Leading Edge Fund: National Centre for Audiology (30702, Canada Foundation for Innovation) in part to Dr. Ewan Macpherson and Dr. Susan Scollie. The authors would like to thank Dr. Marlene Bagatto, Dr. Sheila Moodie, and Dr. John Pumford for their comments, and Dr. Andrew Johnson for his advice regarding statistical methods.

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and the writing of the paper.