RECD Refresher Course 17th November 2004 In Situ Versus Coupler Verification Working Smarter ! Ed Brown Consultant Audiological Scientist MCHAS University of Manchester

RECD Refresher Course 17th November 2004  Audiometry (Custom moulds & Inserts)  HA Prescription  Fine Tuning +++  2 ears, 4 levels, 1 restless child  In Situ HA Verification (50, 65, 80, 90)  Comfortable verifying at 80 and 90 in real ear ?  Speech Testing  Programs, Use, Parent/Child Instruction  Frequency Response Curves What Needs to be Done ?

RECD Refresher Course 17th November 2004  Listening/Comfort Check  Other Programmes  Volume Control  Disabled, enabled, what range ?  Conductive Loss  How much gain, what strategy ?  New Earmoulds  Completion/Collation of Questionnaires  FM Balance/Advantage  …and then the PC crashes What Else Needs to be Done ?

RECD Refresher Course 17th November 2004  How many staff involved in a child’s review ?  What are their skills, experience ?  Do all staff in department work with children ?  How long is your review appointment ?  Variable in the UK  1 person 40 minutes  2 persons 2 hours  MCHAS recommend 2 persons 90 minutes What Resources Do You Have?

RECD Refresher Course 17th November 2004 So what are you going to do?

RECD Refresher Course 17th November 2004  One measurement not four  Child does not need to be present once measured  Can be measured/recorded elsewhere  Gives the option to multitask  Save the RECD  You can build/rebuild (almost) everything from this  Compile your own normative data  Improve accuracy of “first fits”  Easy to monitor changes in canal acoustics  Pattern recognition RECD Advantages

RECD Refresher Course 17th November 2004 RECD Definition Difference between the SPL measured in the real ear and SPL measured in a 2 cc coupler. -=

RECD Refresher Course 17th November 2004 Are RECDs Valid ?  Yes  The RECD/REDD will take you, on average, to within 1 dB of the ear canal SPL  The error will never be more than 5 dB (in 95% of subjects) References: Munro KJ, Davis J. Deriving the real-ear SPL of audiometric data using the "coupler to dial difference" and the "real ear to coupler difference". Ear and Hearing 2003;24: Munro KJ, Hatton N. Customized acoustic transform functions and their accuracy at predicting real-ear hearing aid performance. Ear and Hearing 2000;21:59-69.

RECD Refresher Course 17th November 2004 What about Transducer Type ?  There are issues regarding transducer type/methodology when measuring RECD  There are differences between using an Insert Phone and Hearing Instrument  To do with acoustic impedances  Most pronounce around 2k Hz  May need to measure two RECDs ? References: Munro KJ, Salisbury VA. Is the real-ear to coupler difference independent of the measurement earphone? International Journal of Audiology 2002; 41: Munro KJ, Toal S. Measuring the RECD Transfer function with and Insert and a hearing instrument. Are they the same thing ? In Phonak Focus 33.

RECD Refresher Course 17th November 2004 Measure Each Ear ? Reference: Munro KJ, Buttfield, L. A comparison of real ear to coupler difference values in the right and left ear of adults using 3 earmould configurations, in press, Ear and Hearing  Co operation may be limited  Use one RECD for both ears  In general differences are less than 3 dB  Proviso: no significant wax, normal middle ear function  Probably better than using predicted data

RECD Refresher Course 17th November 2004 How Often ? Reference: Bagatto MP. Optimising your RECD Measurements. Hearing Journal 20001;54:32,  Biggest changes occur within first 2 years of life  RECD can be dB for 1 month old  Not a difficult (relatively) age to measure  Ideally should be measured whenever new earmoulds provided  In practice  Every 3 months until 2 years of age ?  Then every 6 months until 5 years of age ?

RECD Refresher Course 17th November 2004 RECD on Infant

RECD Refresher Course 17th November 2004 Effect of OME

RECD Refresher Course 17th November 2004 So…  There are limitations to an RECD/Coupler compared to In Situ Approach…  …but the clinical advantage for most children probably outweighs this  RECDs are potentially useful for all children  Adults also ?  On going research  Measure In Situ response if you can  At subsequent review appointment ?

RECD Refresher Course 17th November 2004 DSP Exchange (90 min) Pre-Visit (Audio on NOAH, LIFE & LSQ available (on PMS)) “First Fit” aids, previous audiometry, predicted RECD “Insert Phone Audiometry (Custom Earmoulds & Inserts) Measure RECDs Speech Testing Questionnaire Completion Prescription & Verification (2cc Coupler) Frequency Response Curves Initial Evaluation, Hearing Instrument Orientation Programme Assess VC, Processing and Program need

RECD Refresher Course 17th November 2004 In Summary The Clinical Advantages  Can be used to improve accuracy of some manufacturer “first fit” procedures  Only require co-operation for one measurement rather than multiple real ear measurements  Prescription can be verified in coupler without child present and/or “off line”  More effective use of clinic appointment time  Skills (e.g. insert PTA & RECD versus full prescription procedure