AS 1088.8-1987

1 - AS 1088.8-1987 HEARING AIDS - METHODS OF MEASUREMENT OF PERFORMANCE CHARACTERISTICS OF HEARING AIDS UNDER SIMULATED IN SITU
4 - PREFACE
5 - CONTENTS
7 - 1. Scope
7 - 2. Object
7 - 3. Limitations
8 - 4. Explanation of terms
8 - 4.1 Sound pressure level
8 - 4.2 Pinna simulator
8 - 4.3 Ear simulator
8 - 4.4 Occluded-ear simulator
8 - 4.5 Ear canal extension
8 - 4.6 Ear insert simulator
8 - 4.7 Manikin (head and torso simulator)
9 - 4.8 Reference point of a subject or manikin
9 - 4.9 Plane of symmetry of the manikin
9 - 4.10 Axis of rotation of the manikin
9 - 4.11 Reference plane of the manikin
9 - 4.12 Test point
9 - 4.13 Reference input sound pressure level
9 - 4.14 Test axis
9 - 4.15 Test plane (for measurement of the uniformity of the free field wavefront)
9 - 4.16 Azimuth angle of sound incidence
9 - 4.17 Elevation angle of sound incidence (a)
10 - 4.18 Reference position of the manikin in the test space
10 - 4.19 Manikin unoccluded ear gain
10 - 4.20 Manikin unoccluded ear gain frequency response (MFR)
10 - 4.21 Simulated in situ gain (SISG)
10 - 4.22 Simulated in situ gain frequency response (SISGFR)
10 - 4.23 Simulated insertion gain (SIG)
10 - 4.24 Full-on simulated insertion gain
10 - 4.25 Simulated insertion gain frequency response (SIGFR)
10 - 4.26 Manikin unoccluded-ear directional response (MDR)
10 - 4.27 Simulated in situ directional response (SISDR)
11 - 4.28 Simulated insertion directional response (SIDR)
11 - 4.29 Simulated in situ OSPL 90 (output sound pressure level for 90 dB input SPL)
11 - 4.30 Simulated in situ OSPL 90 frequency response
11 - 5. Test equipment
11 - 5.1 Acoustical requirements for the test space
11 - 5.2 Sound source
12 - 5.3 Manikin
12 - 5.4 Ear simulator
12 - 5.5 Ear insert simulator
12 - 5.6 Equipment for the measurement of occluded-ear simulator sound pressure level
13 - 5.7 Equipment for automatic sweep frequency recording
13 - 5.8 Equipment for calibration of free field sound pressure level
13 - 6. Test conditions
13 - 6.1 Choice of test point
14 - 6.2 Ambient conditions
14 - 6.3 Manikin
14 - 6.4 Location of the hearing aid
14 - 6.5 Normal operating conditions for the hearing aid
15 - 7. Measurements
15 - 7.1 General
15 - 7.2 Adjustment of the reference input sound pressure level
16 - 7.3 Manikin frequency response (MFR)
16 - 7.4 Full-on simulated insertion gain measured by the constant reference input SPL method
17 - 7.5 Full-on simulated insertion gain measured by the constant ear simulator SPL method
18 - 7.6 Directional characteristics
19 - 7.7 Simulated in situ OSPL 90 measurements
19 - 8. Frequency response recording charts
22 - APPENDIX A - GENERAL REQUIREMENTS FOR A MANIKIN

Describes test methods which simulate the acoustical effects of a median adult wearer on the performance of a hearing aid. Technically identical with IEC Publication 118-8.

This report applies to the performance characteristics of hearing aids.Measuring methods that take into account the acoustical influence of the wearer on the performance of hearing aids are important, particularly when the results are to be used to assist in the fitting of hearing aids. The information obtained using this report is likely to be more relevant to the fitting of hearing aids than that provided by publications concerned with type approval and quality control such as IEC Publication 118-0: Hearing Aids: Part 0: Measurement of Electroacoustical Characteristics, and IEC Publication 118-7: Hearing Aids, Part 7: Measurement of Performance Characteristics of Hearing Aids for Quality Inspection for Delivery Purposes.The methods specified in this report require a device such as a manikin to simulate the presence of the wearer. Work on a report for a head and torso simulator is in progress. Pending an agreement on a manikin, it has been found necessary to establish certain guidelines for simulated in situ measurements of hearing aids. The recommended methods are described in this report.