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 ear molds) 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.
Key Words
Amplification for children - predicted values - real-ear-to-coupler difference - real-ear
measurements
