Guidelines for the evaluation of hearing aid fitting (2010)
Introduction
There are various selection of hearing aids and hearing-aid adjustments. The method to evaluate the efficacy of the adjusted hearing aid for a hearing-impaired person is the fitting test. The Japan Audiological Society has selected test methods whose usefulness and value were determined during clinical practice. The tests include those presently carried out for evaluating hearing aid fitting, and the methods of testing and evaluation have been published as “Guidelines for the evaluation of hearing aid fitting (2010)”. The aim of these tests is for minimum better fitting of hearing aids.
In these guidelines, test items are selected among those fulfilling the following conditions: test items with (1) obvious decision criteria; (2) the possibility to perform necessary and sufficient evaluation; (3) determined test standards; (4) a reasonable test time; and (5) tests designed for adults.
In this document, guidelines for the following 8 test methods are presented.
- (1)
Measurements of speech performance-intensity functions and speech recognition scores.
- (2)
Assessment of hearing aid fitting from the aspect of tolerance of environmental noise.
- (3)
Measurement of real-ear insertion gain (measurement of sound pressure levels at the eardrum).
- (4)
Measurement of the hearing threshold level and the uncomfortable loudness level (UCL) in sound pressure level (SPL) with an inserted earphone.
- (5)
Aided threshold test in a sound field (functional gain measurement).
- (6)
Prediction of insertion gain and aided threshold from hearing aid characteristics and the pure tone audiogram.
- (7)
Measurement of speech recognition in noise.
- (8)
Assessment of hearing aid fitting using questionnaires.
By performing test combinations properly selected from the above 8 tests, the benefits of a hearing aid can be determined. In the above tests, (1) and (2) are mandatory tests, and (3) to (8) are informative tests. (1) and (2) are mandatory because the primary purpose of hearing aid fitting is to improve speech understanding and the major cause of rejection to wear a hearing aid is intolerance to noise.
Section snippets
Test room
Assuming that hearing aid fitting tests in a sound field are performed in general otolaryngology clinics, the following conditions should be considered:
- (1)
The ambient noise level should not influence the test result.
- (2)
Reverberation of a test sound should not influence the measurement.
- (3)
There should be no mental pressure influencing the decision of the test subject.
Required tests
Measurements of speech performance-intensity functions or speech recognition scores are very important test items to judge whether a person with hearing loss can utilize hearing aids effectively. Assessment that hearing aid users can accept environmental noise is also an important test item to judge whether a person with hearing loss can use hearing aids in daily life. These two test items should be performed whenever a hearing aid is adjusted.
Informative tests
The following tests are useful to evaluate the fitting of a hearing aid, although not necessary to test every time after its adjustment. As the following tests in Sections 4.1 Measurement of real-ear insertion gain (measurement of sound pressure levels at the eardrum), 4.1.1 Test equipment, 4.1.2 Test method, 4.1.3 Evaluation, 4.2 Measurement of the hearing threshold and the uncomfortable loudness level (UCL) in sound pressure level (SPL) with an inserted earphone, 4.2.1 Examination equipment,
Conflict of interest
We declare that we have no conflict of interest in connection with this paper.
Acknowledgements
The present guidelines were made by the members of the Committee on Welfare and Medical Treatment of the Japan Audiological Society.
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