Use of custom-moulded earmoulds to improve repeatability of DPOAE map measurements

Abstract

Objective

Distortion product otoacoustic emission (DPOAE) mapping characterises cochlear function, can include both the 2f1-2f2 and 2f2-2f1 DPOAEs, and shows promise for tracking cochlear changes. DPOAE amplitude measurements are not as repeatable longitudinally as pure-tone audiometry, likely due in part to probe placement sensitivity. We hypothesised that DPOAE level map variation over multiple testing sessions could be minimised by replacing traditional rubber tips with custom-moulded probe tips.

Design

Traditional rubber tips (TRT) and custom-moulded probes tips (CMPT) were used to measure DPOAE level maps repeatedly over five sessions. Probe placement was assessed using a frequency sweep in the ear canal. Repeatability of the DPOAE level maps was assessed using a Bland-Altman analysis. Overall map repeatability was assessed by measuring differences in distortion product amplitude over sessions.

Study sample

Crossover study with a convenience sample size of six adults.

Results

The CMPT frequency sweeps showed reduced variability in probe placement. The repeatability coefficient for individual DPOAEs measurements improved from 6.9 dB SPL with the TRT to 5.1 dB SPL with the CMPT. Map repeatability improved for most subjects with the CMPT.

Keywords:

• Distortion product otoacoustic emissions
• DPOAEs
• ototoxicity
• hearing loss
• cochlear response
• custom earpiece

Geolocation information

This research was conducted at Dartmouth College in Hanover, NH.

Acknowledgments

We gratefully acknowledge the support of Kurt Yankaskas and LCDR Matthew Swiergosz at the Office of Naval Research, Mariana McIlwain, Au.D. of Fairbanks Hearing & Balance Center, and Bethany Wittman, Au.D. of Connecticut Ear, Nose and Throat. Human research was approved by the Dartmouth Committee for the Protection of Human Subjects.

Disclosure statement

No conflicts of interest were related to this study.

Additional information

Funding

This work was supported by the Office of Naval Research under Grant No. N00014-09-1-0859.