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In Situ Versus Coupler Verification Working Smarter !

In Situ Versus Coupler Verification Working Smarter !. Ed Brown Consultant Audiological Scientist MCHAS University of Manchester. What Needs to be Done ?. Audiometry (Custom moulds & Inserts) HA Prescription Fine Tuning +++ 2 ears, 4 levels, 1 restless child

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In Situ Versus Coupler Verification Working Smarter !

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  1. In Situ Versus CouplerVerificationWorking Smarter ! Ed Brown Consultant Audiological Scientist MCHAS University of Manchester

  2. What Needs to be Done ? • 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

  3. What Else Needs to be Done ? • 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

  4. What Resources Do You Have? • 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

  5. So what are you going to do?

  6. RECD Advantages • 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

  7. RECD Definition - = Difference between the SPL measured in the real ear and SPL measured in a 2 cc coupler.

  8. 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;24:100-10. 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.

  9. 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; 41:408-13. Munro KJ, Toal S. Measuring the RECD Transfer function with and Insert and a hearing instrument. Are they the same thing ?. 2004. In Phonak Focus 33.

  10. Measure Each Ear ? • 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 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

  11. How Often ? • Biggest changes occur within first 2 years of life • RECD can be 20-30 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 ? Reference: Bagatto MP. Optimising your RECD Measurements. Hearing Journal 20001;54:32, 34-36

  12. RECD on Infant

  13. Effect of OME

  14. 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 ?

  15. 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) Assess VC, Processing and Program need Measure RECDs Prescription & Verification (2cc Coupler) Speech Testing Frequency Response Curves Questionnaire Completion Initial Evaluation, Hearing Instrument Orientation Programme

  16. In SummaryThe 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

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