Interpreting Speech Results to Optimise Hearing aid Fittings

Transcription

1 Interpreting Speech Results to Optimise Hearing aid Fittings Josephine Marriage PhD BAA Monday 18 th November 2013

2 How has the role of families changed with introduction of NHSP? Early management aims for HI babies to develop on a par with normal hearing peers Parents are key to use of technology Research shows level of family engagement predicts outcomes (Watkin et al, 2007) Hearing aids fitting in first 3 months, referral to CI with aim of implantation by around 12 months Parent observation of hearing responses crucial BUT ABR is absent in many cases, so we have very limited threshold information for HA fitting

3 We are relying on parents for all interventions that change outcomes How has paediatric audiology changed in supporting parents in fulfilling these roles? How do we know if we are being effective in supporting families?

4 What do parents want from functional assessment? 1. Parents wanted to know: level of their hearing with their aids and at what frequencies has there been any change? that hearing aids are closely matching the technology to her hearing profile

5 What would you like to change? 2. Close working with team (especially habilitationist) Continue working closely with AV therapists or ToD - who obviously see the child more. Our audiologists were quick to follow up on an issue raised by the AV therapist which did indeed turn out to be a problem with the implant I would like to see more working in partnership with audiology. Audiologists need to listen to the parent more. If the parent chooses to seek advice and help elsewhere, then the communication needs to be two way process. Audiology must recognise it as an asset not an insult as everyone else is trying to work towards the best possible outcome for the child.

6 What do parents want from functional assessment: 3. CLEAR RESULTS THAT SUPPORT WHAT THEY SEE THEIR CHILD DOING - how can we show parents this? Key to make the link with habilitation. other agencies get a much better insight into the child's everyday behaviour and understanding. As they see them more regularly and have time to have a normal conversation with them. This often reveals a lot more than the test/session itself.

7 What do we know about early hearing aid fittings for infants from NHSP? Research shows that majority of early hearing aid fittings are below targets Strauss and van Dijk, IJA 47 Hearing aid fittings below prescription targets. Only 25% matched 3 or more targets for 65 db input Chear data supports this finding

8 Level dbspl Level dbspl Chear data: Mean difference between targets and gain for non-progressive HL in 33 infants and pre-school (age 7-56 mo) 120 Right Ear 120 Left Ear Target Actual 90 Target Actual Frequency Hz

9 Example of Infant at 6 months Initial fitting Final fitting

10 Speech perception: what needs to be audible?

11 Speech perception: what is inaudible?

12 First priority: Match and verify prescription targets to ensure audibility of speech

13 Running speech is complex and dynamic Audibility does not confirm intelligibility 13

14 What level is needed to understand speech rather than detect a sound? Normally hearing adults can identify sentences with about 50% accuracy when speech level is about 17 db SPL (Plomp, 1978). For mild hearing loss, level required for speech awareness and intelligibility should be about 16 db higher than normal. For severe hearing loss level required for speech awareness and/or intelligibility should be about 28 db higher than normal.

15 Aided Speech Intelligibility Index (Aided SII): proportion of information in speech that is audible through amplification. SII correlates to speech outcomes. SII gives measure of HA fit.

16 Types of speech material: Detection or discrimination? Ling sounds: for detection *** or discrimination Word recognition: McCormick toy test Vocalisations: child s own/others speech/singing S test or other phoneme tests: ***Children need an extra 15dB to move from being able to detect a sound, to being able to discriminate between it and other sounds. This extra 15dB is ESSENTIAL for a child to learn to talk through listening.

17 What parts of speech are detected? How do we know? Use Ling Sounds m oo ee ah sh ss

18 Family or habilitationist reports: /s/ not detected and /sh/ only detected at raised level How does audiologist interpret speech detection information to adjust hearing aid gain? How much increase in gain? What frequencies need to be adjusted? Can we move away from prescription targets?

19 Represent frequency bands across audiogram Hz 500Hz mm u a i sh ss FB F1 F1 LING SOUNDS FB: frequency band 750Hz 850Hz F2 F Hz F2 F1: first formant F2: second formant Hz F2 3000Hz 4000Hz FB FB Source: Ling 1988

20 SPL-o-gram for no detection of /s/ and improved discrimination of /u/ from /i/ Changes of 5 to 8 db can give improved detection of speech sounds. SII changes from 62 to 71 %

21 Speech discrimination testing- 2 years 11 months- ANSD

22 Video Speech recognition testing: ANSD 2 years 11 months What sounds are misheard? /th/ as /kr/ where is the kree? /b/ as nothing (bed as /ed/) /m/ as /f/ (man as fan) How can the hearing aid output be modified?

23 Need formant information for Consonants Taken from AB website Tools for Schools

24 Check crib sheet of acoustic features for consonants 1 st Formant 2 nd Formant 3 rd Formant 4 th Formant /kr/ /thr/ /b/ /m/ Hz /f/

25 Another method to assess what sound can be discriminated: ASSE test

26 ASSE results presented as:

27 Good audiology relies on habilitation Habilitation relies on good audiology Parents want demonstration of aided access to speech Speech testing needs to be interpreted in a systematic way to fine-tune hearing aid fitting Small adjustments to amplification can make perceptual difference to child Parents can give clear observations on child s speech detection and discrimination Workshop tomorrow at 2.15 on practical ideas for integrating early listening skills with audiology

28 Thank you for listening and to parents and families for questionnaire responses