Real-ear to coupler difference: importance on the pediatric amplification

Abstract

INTRODUCTION: The specific acoustic characteristics of the ear of babies and infants make it necessary to use acoustic transforms in pediatric hearing aid (HA) selection and fitting process. In this review of literature the “Real Ear to Coupler Difference (RECD)” is described. DESCRIPTION: The RECD is the measure of the difference in sound pressure level (SPL) generated in the external ear canal and the SPL generated in the 2cc coupler, given the same input signal and is used at different stages of the HA selection verification in the pediatric population. The insert earphone transducer is commonly used to obtain this measure, being coupled to a foam tip or custom ear mold – these coupling systems yield different results. In children with normal external and middle ears, the RECD presents positive values at all frequencies. Given the same anatomical and physiological conditions and the same coupling system, there is no significant difference between the RECD for left and right ears. There are great RECD values between subjects, denoting the importance of the individual measurements. An example of the clinical application of RECD is presented. FINAL CONSIDERATIONS: While it is an objective measure, the interpretation of the validity of the results of the RECD is subjective, and the professional must be properly trained to do so. It is recommended that the RECD is obtained with the insert earphone and custom ear mold, and the reassessment made at each ear mold change.