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Real-ear-to-coupler difference predictions as a function of age for two coupling procedures
Marlene P Bagatto1, Susan D Scollie, Richard C Seewald
1National Centre for Audiology, University of Western Ontario, London.
Insights
New research offers predicted real-ear-to-coupler difference (RECD) values for infants and children, improving upon older methods for hearing aid fitting. While not replacing individual measurements, these estimates offer better accuracy when direct RECD measures are not feasible.
Area of Science:
- Audiology
- Pediatric audiology
- Hearing instrument science
Background:
- Current pediatric hearing instrument prescription relies on broad age categories for real-ear-to-coupler difference (RECD) values.
- Existing RECD prediction methods were based on measurements using standard acoustic immittance probe tips.
Purpose of the Study:
- To develop normative RECD predicted values for foam/acoustic immittance tips and custom earmolds across a continuous age range.
- To create regression equations for predicting RECDs based on age in months for pediatric populations.
Main Methods:
- Collected RECD data from 392 infants and children.
- Utilized both acoustic immittance tips (n=141) and custom earmolds (n=251) for data collection.
- Developed normative regression equations to predict RECD values by age.
Main Results:
- Predictive equations for RECDs by age provided gross estimates due to significant between-subject variability.
- Estimates were within +/- 4.4 dB (acoustic immittance tips) and +/- 5.4 dB (earmolds) for 95% of measures.
- Continuous age predictions offer improved accuracy over previous normative values when individual RECD measurements are not possible.
Conclusions:
- The developed RECD predictive equations offer more accurate estimates than previous methods for pediatric hearing aid fitting when individual measurements are not feasible.
- These estimates should not substitute precise, individual RECD measurements.
- Further research may refine these predictions for better clinical application.
Abstract:
The predicted real-ear-to-coupler difference (RECD) values currently used in pediatric hearing instrument prescription methods are based on 12-month age range categories and were derived from measures using standard acoustic immittance probe tips. Consequently, the purpose of this study was to develop normative RECD predicted values for foam/acoustic immittance tips and custom earmolds across the age continuum. To this end, RECD data were collected on 392 infants and children (141 with acoustic immittance tips, 251 with earmolds) to develop normative regression equations for use in deriving continuous age predictions of RECDs for foam/acoustic immittance tips and earmolds. Owing to the substantial between-subject variability observed in the data, the predictive equations of RECDs by age (in months) resulted in only gross estimates of RECD values (i.e., within +/- 4.4 dB for 95% of acoustic immittance tip measures; within +/- 5.4 dB in 95% of measures with custom earmolds) across frequency. Thus, it is concluded that the estimates derived from this study should not be used to replace the more precise individual RECD measurements. Relative to previously available normative RECD values for infants and young children, however, the estimates derived through this study provide somewhat more accurate predicted values for use under those circumstances for which individual RECD measurements cannot be made.