Optimising Outcomes for Speech Mapping

Transcription

1 Optimising Outcomes for Speech Mapping Jan Pollard Chief Audiologist Sonic Craig Lett Audiologist ECS

2 Back to Basics

3 What is the point of all of this? Optimising the fitting for best patient outcomes and satisfaction Better hearing outcomes (Ching et al 2010) Happier patients Fewer follow up appointments (Kochkin, 2001) They help us reach our goals for a successful hearing aid fitting

4 What is the goal of a hearing aid fitting???? Normal sound? Speech audibility? REMs confirm that what we think we are doing is, in fact, what we are doing Inform and guide our clinical work For REMs to be of benefit, we need some kind of gold standard

5 Real Ear Reality? Scenario: New hearing aid wearer Used a real ear system to measure the REAR Adjusted gain levels to match NAL-NL2 targets Reset hearing aids to first fit algorithm

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7 The Gold Standard Researched, verified prescriptive targets REMs show how well we are meeting these targets The easy part? Hearing aid software vs verification software Proprietary targets too low HA software NAL-NL2 targets too low (Sanders et al. 2015)

8 NAL-NL2 vs Proprietary Fitting Targets 55dB SPL input 75dB SPL input (Sanders et al, 2015)

9 NAL-NL2 vs NAL-NL2 55dB SPL input 75dB SPL input (Sanders et al, 2015)

10 Making the first measurement Stop!

11 The Probe Tube Conundrum To calibrate or not to calibrate Always put on a new tube Always calibrate it Frequency response of the probe tube Probe tube calibration removes the acoustic response of the tube.

12 Probe Tube Cleaning

13 Probe Tube Placement Probe tip 6mm of TM Probe 6 mm from eardrum provides measure within 2 db of what is at eardrum at 6K Hz and within 4 db of what is at 8 K Hz Reflective interference causes null points, which show up as reduced measured gain

14 The Stimulus Comparing apples with zucchini All sounds created equal, but some are more equal than others The stimulus used will affect the hearing aid gain when matched to target. Different stimuli contain different frequency information. Matching to targets with one does not necessarily mean you have matched targets with another, so what should we use and what are the implications of using an alternative? ISTS / Carrots / Rainbows?

15 Stimulus

16 PERCENTILE ANALYSIS

17 Verification Is it just meeting a target? Are there other measures that could assist in trouble shooting fittings? Can the SNR be improved by looking at the percentile analysis?

18 Peak vs LTAS 65 db PEAK LTAS 12 db

19 Target Lines and Speech-o-gram 65 db Harvey Dillon NAL NL2 Targets

20 NAL-NL1 NAL-NL2 65 db Target

21 Speech is Dynamic LTASS is an average intensity over time How much of the signal occurs at each intensity level around that? 30 db

22 Examples-Speech Noise (50th, 65th, 80th & 90th Percentiles)

23 PRN Speech Weighted (Byrne)

24 Linear Gain

25 ISTS- Input (50th, 65th, 80th & 90th Percentiles) 90 th Peaks 80th 65th 50 th Valleys Number shows compression ratio *

26 ISTS- Aid Output (50th, 65th, 80th & 90th Percentiles) 2 LTAS measurementssame output

27 Sloping loss- (50 th, 65 th, 80 th & 90 th Percentiles) High Frequency Compression

28 GAIN vs FREQUENCY Short attack/release vs long Long attack/release times: - The compressor work too slowly to respond to the rapid changes in speech level - Acts more like a linear aid Percentiles Study Group 2014

29 Percentiles of short vs long attack/release times As compressors work faster, the softer levels are amplified more and the louder sounds less The dynamic range of the output signal is different Percentiles Study Group 2014

30 LTASS vs Percentile Analysis The LTASS curve represents the average level The same LTASS curves can have different percentile analysis spreads The is represents different sound outputs Adaptive features interact together to affect the speech dynamic

31 Fine Tuning with Percentile Analysis Change the compression to improve the output spread to improve speech discrimination Match an old aid to a new aid to improve client acceptance of new aids- It just doesn t sound the same/right Improve SNR by ensuring compression correct

32 Successful Fittings The client sees the improvement Speech discrimination, especially in noise, is improved The client wears the hearing aids!

33 References Ching, T.Y., Scollie, S.D., Dillon, H., Seewald, R. (2010) A cross-over, doubleblind comparison of the NAL-NL1 and the DSL v4.1 prescriptions for children with mild to moderately severe hearing loss. Int J Audiol 49(Suppl 1):S4-15 Kochkin S. (2001) MarkeTrak VIII: Reducing patient visits through verification and validation. Hearing Review 18(6): Sanders, J., Stoody, T., Weber, J., & Mueller H.G. (2015) Manufacturers NAL-NL2 fittings fail real ear verification. Hearing Review 21(3):24

34 Thank you