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J Am Acad Audiol 2018; 29(06): 520-532
DOI: 10.3766/jaaa.17007
Articles
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Evaluation of the Repeatability and Accuracy of the Wideband Real-Ear-to-Coupler Difference

Jonathan M. Vaisberg
*   National Centre for Audiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
†   Graduate Program in Health & Rehabilitation Sciences (Hearing Science), Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
,
Paula Folkeard
*   National Centre for Audiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
,
John Pumford
‡   Audioscan, a Division of Etymonic Design Incorporated, Dorchester, ON, Canada
,
Philipp Narten
*   National Centre for Audiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
§   Lübeck University of Applied Sciences, Lübeck, Germany
,
Susan Scollie
*   National Centre for Audiology, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
¶   School of Communication Sciences and Disorders, Faculty of Health Sciences, University of Western Ontario, London, ON, Canada
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Publikationsverlauf

Publikationsdatum:
29. Mai 2020 (online)

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Abstract

Background:

The real-ear-to-coupler difference (RECD) is an ANSI standardized method for estimating ear canal sound pressure level (SPL) thresholds and assisting in the prediction of real-ear aided responses. It measures the difference in dB between the SPL produced in the ear canal and the SPL produced in an HA-1 2-cc coupler by the same sound source. Recent evidence demonstrates that extended high-frequency bandwidth, beyond the hearing aid bandwidth typically measured, is capable of providing additional clinical benefit. The industry has, in turn, moved toward developing hearing aids and verification equipment capable of producing and measuring extended high-frequency audible output. As a result, a revised RECD procedure conducted using a smaller, 0.4-cc coupler, known as the wideband-RECD (wRECD), has been introduced to facilitate extended high-frequency coupler-based measurements up to 12.5 kHz.

Purpose:

This study aimed to (1) compare test–retest repeatability between the RECD and wRECD and (2) measure absolute agreement between the RECD and wRECD when both are referenced to a common coupler.

Research Design:

RECDs and wRECDs were measured bilaterally in adult ears by calculating the dB difference in SPL between the ear canal and coupler responses. Real-ear probe microphone measures were completed twice per ear per participant for both foam-tip and customized earmold couplings using the Audioscan Verifit 1 and Verifit 2 fitting systems, followed by measurements in the respective couplers.

Study Sample:

Twenty-one adults (mean age = 67 yr, range = 19–78) with typical aural anatomy (as determined by measures of impedance and otoscopy) participated in this study, leading to a sample size of 42 ears.

Data Collection and Analysis:

Repeatability within RECD and wRECD was assessed for each coupling configuration using a repeated-measures analysis of variance (ANOVA) with test–retest and frequency as within-participants factors. Repeatability between the RECD and wRECD was assessed within each configuration using a repeated-measures ANOVA with test–retest, frequency, and coupler type as within-participants factors. Agreement between the RECD and wRECD was assessed for each coupling configuration using a repeated-measures ANOVA with RECD value, coupler type, and frequency as within-participants factors. Post hoc comparisons with Bonferroni corrections were used when appropriate to locate the frequencies at which differences occurred. A 3-dB criterion was defined to locate differences of clinical significance.

Results:

Average absolute test–retest differences were within ±3 dB within each coupler and coupling configuration, and between the RECD and wRECD. The RECD and wRECD were in absolute agreement following HA-1-referenced transforms, with most frequencies agreeing within ±1 dB, except at 0.2 kHz for the earmold, and 0.2–0.25 kHz for the foam tip, where the average RECD exceeded the average wRECD by slightly >3 dB.

Conclusions:

Test–retest repeatability of the RECD (up to 8 kHz) and wRECD (up to 12.5 kHz) is acceptable and similar to previously reported data. The RECD and wRECD are referenced to different couplers, but can be rendered comparable with a simple transform, producing values that are in accordance with the ANSI S3.46-2013 standard.

Key Words

coupler - ear canal - hearing aids - instrumentation - probe tube - RECD - reliability and validity - repeatability - verification

This work was funded with support from Audioscan, a division of Etymonic Design Incorporated.


This work was presented at the 2016 annual meeting of the American Academy of Audiology (AudiologyNOW!) in Phoenix, AZ, April 15, 2016.


 

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