Real-Ear-to-Coupler Difference

Callisto™ Support

The Real Ear to Coupler Difference (RECD) is a measurement that accounts for the decibel difference across frequencies between SPL measured in the coupler and the SPL measure in the real ear, produced by the same transducer generating the same signal. This ensures that information about the patient’s occluded ear canal characteristics is obtained.

Due to the physically smaller size of the ear canals for infants and children compared to adults, and because it would be very difficult to do real-ear verification on them, the RECD is an important measurement in the pediatric hearing aid fitting process. It enables clinicians to verify the frequency/gain characteristics of the child’s hearing aid while it is attached to the 2cc BTE coupler, without the need to have the child’s ear physically present. Since children have physically smaller ears than adults, and smaller ears equals higher SPL, not taking the RECD into account would likely lead to over-amplification. For more information on RECD and the recommended guidelines for pediatric hearing aid fittings, please refer to the references at the end of this document.

There are two ways of measuring the RECD: with the patient’s ear mould or with the SPL60 RECD probe tip. Measuring with ear moulds will be a bit more precise than measuring with the SPL probe, however; in situations where a quick measurement is needed, using the SPL probe will be much quicker than measuring with the ear mould. In situations where no measurement can be obtained, it is recommended to use age appropriate, predicted RECD values. Instructions for all three methods are detailed below.

The Callisto™ with Coupler Base

An REM headset/reference microphones

An RECD tube found in the SPL60 Probe tip set, which will be connected the ear mould tube via a tube nipple

2 cc coupler connected to an adaptor for the BTE

Launch the Callisto™ software from your patient management system, Noah or OtoAccess®and click on the REM440 tab