Sound decision making in frequency lowering. Christine Jones, AuD Phonak

Transcription

1 Sound decision making in frequency lowering Christine Jones, AuD Phonak

2 Agenda Why the bandwidth frenzy Methods of frequency lowering Clinical questions and scientific evidence Optimization and verification 2

3 The effects of high-frequency amplification on the perception of /s/ - children 1.0 Male Female Child 0.8 Proportion correct Low-Pass filter frequency (khz) > 55 db HL (N=14) < 55 db HL (N=4) 3 Stelmachovicz et al. 2001

4 Word learning improves as a function of bandwidth 5 3/24/2014 ChJones - Phonak Pediatrics - ISHA» Pittman, 2010

5 Understand patients functional versus reported bandwidth 6

6 ANSI standard bandwidth limitation 7

7 Bandwidth reporting: Nyquist frequency Aliasing error 8

8 Extended bandwidth you can measure Phonak Sky Q-M13 SoundRecover OFF Competitor A premium HI with extended bandwidth Competitor B premium HI with extended bandwidth 9

9 SoundRecover you can hear /s/ /s/ Phonak Sky Q-M13 SoundRecover ON Phonak Sky Q M13 SoundRecover OFF Competitor A premium HI with extended bandwidth Competitor B premium HI with extended bandwidth 10

10 Agenda Why the bandwidth frenzy Methods of frequency lowering Clinical questions and scientific evidence Optimization and verification 11

11 Bernafon s Frequency Lowering Classification From Bernafon White Paper Frequency transposition Sound Recover Freq Composition 12 3/24/2014 Change your footer by: Insert > Header & Footer

12 Complete shifting with a constant factor Frequency Transposition Scheme 1 10 khz Output frequency 1 khz 100 Hz 100 Hz 1 khz 10 khz Input frequency

13 Strategy 1 frequency transposition Consequences of a high frequency hearing loss Level (db) Cut-off-Frequency Frequency (khz)

14 Partial Transposition Frequency Transposition Scheme 2 10 khz Output frequency 1 khz 100 Hz 100 Hz 1 khz 10 khz Input frequency On/off switching, only active when high frequency speech energy detected

15 Consequences of high frequency hearing loss Strategie 2 frequency transposition level (db) Frequency (khz) Cut-off-Frequency

16 Frequency Shifting, Frequency Lowering Output Frequency -> Output frequency 10 khz 10 khz 10 khz Cut-off frequency 1 khz Output frequency 1 khz 100 Hz 100 Hz 100 Hz 100 Hz 1 khz 10 khz 100 Hz 1 khz 10 khz 100 Hz 1 khz 10 khz Output frequency 1 khz Input frequency Input frequency Input Frequency -> Input frequency

17 Consequences of high frequency hearing loss Non-linear frequency compression level (db) Frequency (khz) 18 Technology Options for Fitting Children, Sound Foundation, Chicago, Stefan

18 Considerations when selecting frequency lowering technologies Are high frequency consonants audible? Can /s/ be made audible Can /s/ and /sh/ be distinguished Is vowel perception disrupted? How is overall sound quality Can settings be verified electro-acoustically? Behaviorally? 19

19 Agenda Why the bandwidth frenzy Methods of frequency lowering Clinical questions and scientific evidence Optimization and verification 20

20 Clinical questions 21 Music Mild HL Acclimati zation Noise ChJones - Phonak Pediatrics - ISHA 3/24/2014

21 Should I apply FrLo for musicians and patients who enjoy music? 22 Parsa et al (2013) No impact was found, indicating that a range of NFC parameters exists that will not adversely affect sound quality for hearing impaired listeners. Miranda Uys (2012) Greater appreciation and enjoyment of music was reported with Sound Recover than with conventional signal processing. Participants were adults with moderate to severe SNHL. The following musical qualities were compared between conditions (n=40, blinded) ChJones - Phonak Pediatrics - ISHA 3/24/2014

22 Musical qualities with SR PARAMETER NFC COMPARED TO TRADITIONAL PROCESSING STATISTICALLY SIGNIFICANT QUALITY RATINGS with NFC Tinniness Improved Yes Reverberance Improved Yes Loudness No change No Fullness Improved No Crispness Improved No Naturalness Improved No Fidelity Improved No Pleasantness Improved No Identification of instruments Improved RECOGNITION with NFC Discrimination of rhythm Improved Yes Yes Distinguish between high and low notes Improved No Distinguish lyrics Improved No Distinguish melody Improved No 23 Uys, 2012

23 Clinical applications for music May improve some dimensions of musical appreciation For aficionados, provide a music program with it on and off to allow the individual to determine their preferred listening condition 24

24 How long will it take for a patient to achieve maximum benefit? Most subjects show some initial benefit at the time of fitting but there is evidence with children that performance can continue to improve over at least 6 months time after initial NFC fittings. Data published by Wolfe (2011) showed that a group of 15 children with moderate to moderately-severe hearing loss continued to improve on recognition of high frequency phonemes and listening in noise at 6 months of NFC use compared to data collected after 6 weeks of use. This study shows there is some acclimatization effect with NFC. Ellis (2012) also showed limited evidence of some acclimatization period with adults using NFC. 25

25 Sub 1 26» Glista, 2012

26 Sub 3 27» Glista, 2012

27 Sub 5 28» Glista, 2012

28 Acclimatization Unique patterns of results may emerge for each patient For at least some patients, benefit may improve over at least a 6 month period 29

29 Does FrLo have benefits in noise? Some people benefit, others do not. To better understand what those patient variables are, we need further research. Several studies have reported that on average, subjects ability to understand in noise improved with Sound Recover compared to conventional amplification. Bohnert (2010) demonstrated that 7/11 subjects with severe to profound SNHL performed better in noise with SR than with conventional amplification. Wolfe (2011) showed that children with up to moderately-severe SNHL improved on the BKB speech test in noise after 6 months of NFC use. 30

30 Is there benefit for FrLo with mild to moderate HL? db HL Right Left n = Frequency (Hz)» Wolfe, in press, 2014

31 Aided Thresholds NLFC On NLFC Off Wideband K 6K 8K /sh/ /s/» Wolfe, in press, 2014 n = 11

32 Phonak Phoneme Perception Test Detection Task NLFC On NLFC Off Wideband /sh/ Low /sh/ High /s/ Low /s/ High» Wolfe, in press, 2014 n = 11

33 Phonak Phoneme Perception Test Recognition Task NLFC On NLFC Off Wideband /sh/ Low /sh/ High /s/ Low /s/ High» Wolfe, in press, 2014 n = 11

34 UWO Plural Test NLFC On NLFC Off Wideband» Wolfe, in press, 2014 n = 11

35 UWO DFD Test NLFC On Wideband» Wolfe, in press, 2014 n = 11

36 BKB-SIN db SNR NLFC On NLFC Off Wideband» Wolfe, in press, 2014 n = 11

37 Conclusions There is no evidence of degraded performance in quiet or in noise with the use of NLFC for children with mild SNHL May provide improved detection for /s/, particularly female /s/ Decision should be made on a case by case basis whether the patient has adequate audibility of high frequencies» Wolfe, in press, 2014

38 Agenda Why the bandwidth frenzy Methods of frequency lowering Clinical questions and scientific evidence Optimization and verification 39

39 40

40 Verification assistant Test box

41 Verification assistant Test box or REM

42 Verification assistant Test box or REM

43 Verification assistant Test box or REM

44 The UWO Plurals and Ling-6 HL package UWO Plurals test Tests perception of high frequency speech sounds Specific to the English language Measures the listener s ability to detect final consontant eg. /s/ and /z/ in words 45

45 UWO Ling 6 test Developed as a speech sound detection measure Measurement of hearing threshold per sound Aided and unaided testing conditions Ling 6 sound m ah ee oo sh s Example mom bath bee boo fish kiss 46

46 Calibration When? Before using test for the first time (or after equipment recalibration) Not necessary before every test How? Adjust VU meter on the audiometer using Track 1 (calibration tone) to zero Use Track 2 (calibration broadband noise) to measure output level in db A with sound level meter (SLM) The SLM reading of 55 db A should correspond to a dial setting of 65 db HL, at the position corresponding to the center of the listener s head at 0 degrees 47

47 How is it administered? 1. Instruct the listener You will hear a woman s voice saying some words. Point to the picture that matches the word that you hear. Listen carefully and give it a guess if you are not sure. 2. Present 2 word lists (freefield) 3. Child points to picture that corresponds to what they heard (closed set) 4. Repeat step 1 & 2 in the comparative test condition (ie. aided versus unaided) 48

48 Scoring When are the two scores significantly different? Example: Test condition A 54% Test condition B 71% Find the lower of the two scores on the critical difference table Match with the correct column (30 or 60 item presentation) 30 item presentation not significant (71 < 75) 60 item presentation significant (71 > 69) 49

49 Phonak Phoneme Perception Test (PPT) NOAH based test for Assessing hearing performance Comparison of fittings, products, parameters Optimization of fittings Validation of fittings Tracking auditory progress, acclimatization 50

50 Detection test and improving fittings 51

51 Distinction 52

52 Recognition 53

53 Proposed flow chart of fine tuning actions Strengthened? Weakened? 54

54 Take home There are factors beyond the audiogram that dictate benefit, preferences and optimal parameters with frequency lowering In any fitting, determine if patient has access to female /s/ and /sh/, if not frequency lowering may be necessary When setting parameters, use the weakest possible settings to provide audibility while having a minimal impact on lower frequencies and avoiding confusions 55

55 Thank you