eval Paper on evaluation for MCHAS website for discussion by keralaguest

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									Paper on evaluation for MCHAS website: for discussion/comment.



                     Evaluation of children’s hearing aids

Summary

Evaluation is the process of gathering information and reaching a judgement

about the experience of amplification in both clinical and real world situations.

This paper outlines the purposes of evaluation, the reasons for doing it, and

the main techniques that can be employed. At the end is

   an appendix with a list of questionnaires etc suitable for use with children.

   a list of references for readers who wish to follow up the published

    literature.

   a list of abbreviations used in the text.



What is evaluation?

The process of hearing aid fitting comprises a number of stages.

1. the generation of amplification targets for the hearing aid wearer. It is

recommended that this is done using prescriptive formulae that have been

published in peer reviewed journals rather than proprietary software supplied

by hearing aid manufacturers.

2. the selection and fitting of a hearing aid that has the necessary gain output

and other required features.

3. verification, which involves measuring the hearing aid performance to

ensure that it meets the amplification targets. This should be done using Real

Ear Measures (either in situ REAR or in the 2cc coupler with measured RECD

accounted for).



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4. evaluation, which involves gathering relevant information about the

effectiveness of the amplification provided. An important aspect of this is

subjective “real world” evaluation (e.g. questionnaires) which is increasingly

becoming a part of the evaluation process in modernised hearing aid services.

“Real world” evaluation is desirable because even if a hearing aid is producing

the gain required by the prescriptive targets, this may not be translated into

optimal speech recognition (as indicated by speech tests or predicted

audibility measures) and/or it may not be providing a listening experience in

everyday contexts that is helpful or pleasant for the user. Therefore,

evaluation is now recognised to be an essential element in ensuring that

hearing aid wearers are receiving the intended benefit of amplification.



How can it be done?

Methods of hearing aid evaluation include:

   Measuring functional gain (eg aided threshold measurement).

   Real Ear Measurements (REMs). These are more correctly placed in the

    verification stage of the fitting process, but are sometimes referred to in the

    context of evaluating hearing aid performance.

   Sound and/or speech recognition tests (eg Ling, Parrot, CCT, Manchester

    picture, AB word lists, BKB sentences, FAAF tests.)

   Observation/video recording/checklists/measures of speech/spoken

    language/communication development.

   Calculation of predicted audibility indices (eg SII, AAI).

   Questionnaires about matters such as the extent to which hearing aids are

    used, the benefit experienced by the user, residual disability (or limitation



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    to hearing in everyday contexts), residual handicap (or impact of hearing

    loss on lifestyle) and overall satisfaction. They may also seek information

    about the effect of hearing aids on significant others and on the user’s

    quality of life. In the case of children, such questionnaires may involve

    proxy reporting, in which an appropriate adult (such as a parent or ToD)

    provides information additional to or on behalf of the child.

   Psychoacoustic (listening) and electroacoustic checks. These are more

    commonly perceived as part of essential ongoing management and are

    important in maintaining hearing aids’ optimal performance over time, but

    do not help in evaluating aspects such as use, benefit or satisfaction.

   Assessing the ergonomic aspects of hearing aids can be important as

    these influence satisfaction – reliability, robustness, comfort (including

    earmoulds) and cosmetic features.



The evaluation process seeks a comprehensive picture of how effective

hearing aids are in real world situations. This can then prompt further enquiry

as to factors that hinder or enhance the hearing aids’ effectiveness for an

individual.



All of these methods listed above have strengths and weaknesses. The more

“objective” measures that involve tests in a clinic or classroom are believed to

produce “hard” data free from the bias that may affect “subjective” self-reports.

However they usually produce data about artificial situations (e.g.

performance on a speech test) and test instruments tend to require calibrated

equipment and can be time-consuming. Subjective measures (e.g.



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questionnaires) have the advantage that they can produce data about real

world listening contexts that are relevant to the hearing aid user and they are

relatively quick and easy to administer. However, in the case of children in

particular, there is little evidence about the extent to which they align with

more “objectively” gathered information. Despite this, they can still be useful in

giving an informative, and systematically obtained account of the respondents’

views (eg child, parent , ToD).



What questionnaires are available?

The appendix to this paper contains a list of twenty different questionnaires

that have been developed for use with children. Many of these have been

developed in the USA and few have any published data about their reliability,

validity or sensitivity. None have published norms for either normal hearing or

hearing-impaired populations. Hence it can be seen that there is a pressing

need for further research to establish this sort of benchmark information. In

the meantime, the MCHAS team recommend that in addition to whatever

evaluation is currently carried out, services should begin to use routinely two

questionnaires which have been modified or developed for use in the UK.

These are:

   The Listening Inventory For Education – Individual Hearing Profile (LIFE-

    IHP).

   The Listening Situations Questionnaire (LSQ), Parent and Child versions.

Data are being gathered about the validity, reliability and sensitivity of these

measures. Both have had recent modifications: check www.mchas.man.ac.uk

for the latest versions.



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These questionnaires are most appropriate for children aged seven years or

more. Therefore the MCHAS team currently recommends the Parent

Evaluation of Aural/oral performance in Children (PEACH) questionnaire,

which was developed in Australia for use with infants onwards. However, a

recent development in the UK which should help hearing aid evaluation

greatly at the younger end of this age range is the launch of the Early Support

Project and specifically the Common Monitoring Protocol (CMP) for deaf

babies. This has been designed to meet the need for standardisation in

monitoring all aspects of early development in deaf babies and children: see

www.earlysupport.org.uk . Monitoring the hearing aids in a systematic way is

built into this process within the “attending, listening and vocalisation” section

of the CMP and also to some extent within the “communication” section. The

Level Two materials also address attending/listening skill/vocalisation

(specifically, detailed recording of phoneme development) which are directly

relevant to assessing the benefit from hearing aids. Relevant information

about the development of listening skills and babies’ and toddlers’ responses

to amplification is being systematically collected where these protocols are in

use. Further development of the actual practice of extracting and sharing

relevant information for the specific purpose of a hearing aid review is

necessary.



Why should we use questionnaires?

The main advantages of using questionnaires can be summarised as follows:

   They help to promote better understanding about children’s needs and

    priorities in relation to the use, benefit from and satisfaction with their



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    amplification equipment (hearing aids, fm systems, other assistive listening

    devices).

   They can enhance education and hearing aid service quality by identifying

    needs which can then be more closely examined. Ways of meeting these

    needs are varied and may be innovative and personalised. For example,

    there may be a need for a change in hearing aid settings or activation of

    features (second listening program, directional microphone); provision of

    additional equipment such as fm systems or sound field systems; provision

    of practical help and emotional support or counselling in relation to

    amplification; provision of guidance to mainstream teachers and Learning

    Support Assistants.

   Collecting information in a common format creates a record of the child’s

    experience with hearing aids which is more easily shared between the

    family and service providers and across different areas if the family moves

    (subject to data protection requirements).

   Collecting “standard” information facilitates research into the hearing aid

    evaluation process. Local data could be fed back to researchers or into a

    national database, and with other information also being recorded on

    patient management systems (such as type of hearing aid, features, fitting

    parameters etc) these and other variables (staffing ratios, provision of

    support etc) could be statistically analysed to provide insight into the

    factors which promote effective services and successful outcomes.

   Use of questionnaires intensifies awareness of the use of audition in the

    user and managers of the amplification systems.




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When should we use them?

   Before a hearing aid review, to facilitate the exchange of information

    between families, education and health professionals.

   At times of transition (eg into new class, school) to assess the new

    situation.

   At regular reviews of progress (according to the individual child’s level of

    support).

   To evaluate a particular change in amplification provision or support (eg

    switch to DSP, ITE, CI provision, introduction of personal or Sound Field

    fm systems).



Conclusion

At present, our knowledge of how best to evaluate children’s hearing aids is

much less advanced than other stages of the fitting process. We need more

research into the following areas:

   the content of questionnaires (which is related to the purpose of using

    them).

   the reliability, validity and sensitivity of different questionnaires and norms

    for hearing and hearing-impaired populations.

   the timing and frequency of evaluation measures.

   the administration of questionnaires : interview/self report/observations;

    use of pictures/computers.

   the different perspectives of parents, ToDs and peers in relation to both

    their own and the children’s experiences with hearing aids; how these

    perspectives mesh together.



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   The value to parents, children, education, health and other services of

    using questionnaires as well as other methods of evaluation.



Despite the lack of definitive information on these topics, there are strong

reasons to introduce a more systematic evaluation process which includes

children’s real world experiences, and there are adequate if not yet ideal tools

for doing so.



List of abbreviations used in the text

REAR – Real Ear Aided Response

RECD – Real Ear to Coupler Difference

REMs- Real Ear Measures

Ling – Ling 6 sounds test

Parrot/Phoenix – recorded automated version of the McCormick Toy Test *

CCT – Consonant Cluster Test (available from J.Marriage, CHEAR)

AB – Arthur Boothroyd word lists*

BKB – Bamford-Kowal-Bench sentence tests*

FAAF – Four Alternative Auditory Feature test*

SII – Speech Intelligibility Index

AAI – Aided Audibility Index

ToD Teacher of the Deaf

MCHAS – Modernisation of Children’s Hearing Aid Services

LIFE-IHP _ Listening Inventory For Education – Individual Hearing Profile

LSQ – Listening Situations Questionnaire

PEACH – Parent Evaluation of the Aural/oral performance of Children



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ESP – Early Support Project

CMP – Common Monitoring Protocol

DSP – Digital Signal Processing

ITE – In The Ear

CI – Cochlear Implant



* Available from the Medical Research Council Institute of Hearing Research,

Nottingham.

Note: Phoenix, Manchester picture test and AB word lists are available from

www.soundbytesolutions.co.uk



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Andrews, E. (2005). The Early Support Programme (Personal communication)

ANSI (1993). ANSI S3.5 Draft v3.1-1993 Proposed American National

Standards methods for calculation of the speech intelligibility index. New York,

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