Question
When verifying open canal fittings, what is the suggested way to measure real-ear to coupler difference (RECD)?
Answer
At this point, there is no good way to measure RECD when fitting open. If you can't measure real ear aided response (REAR) with the instrument in the ear, you are going to have some problems. The main issue with using RECD to fit an open canal instrument is that you are going to end up attempting to give a lot of amplifier gain in places where no insertion gain is needed.
This Ask the Expert was based on information in Dr. Rickett's course, Open Canal Fittings: Considerations Regarding Prescriptive Methods and Function of Special Hearing Aid Features (include link). More information on verifying open canal fittings can also be found in the course, Open Canal Fittings: Unique Acoustic and Verification Considerations (include link) by Dr. H. Gustav Mueller.
Todd A. Ricketts, Ph.D, CCC-A, FAAA, is an associate professor at the Vanderbilt Bill Wilkerson center for Otolaryngology and Communication Sciences and Director of the Dan Maddox Hearing Aid Research Laboratory. Todd has published more than sixty scholarly articles and book chapters. To date he has presented over 150 scholarly papers/poster presentations, short courses, mini-seminars, and workshops to professional and scholarly conferences both nationally and internationally. He continues to pursue a federally and industry funded program studying various aspects of hearing, hearing aids and cochlear implants. He was named a Fellow of the American Speech Language and Hearing Association in 2006 and his article "Directional benefit in simulated classroom environments" received the Editors award from the American Journal of Audiology at the 2008 AHSA convention. He also is a past editor-in-chief of the quarterly journal Trends in Amplification and is the current chair of the Vanderbilt University Institutional Review Board Behavioral Sciences Committee.
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