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BS EN IEC 60318-8:2022

BS EN IEC 60318-8:2022

$167.15

Electroacoustics. Simulators of human head and ear – Acoustic coupler for high-frequency measurements of hearing aids and earphones coupled to the ear by means of ear inserts

Published By Publication Date Number of Pages
BSI 2022 38
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IEC 60318-8:2022 describes an acoustic coupler for loading a hearing aid or insert earphone with a specified acoustic impedance when testing its acoustic performance, in the frequency range up to 16 kHz. It is suitable for air-conduction hearing aids and earphones, coupled to the ear by means of ear inserts, earmoulds or similar devices. The acoustic coupler does not simulate the human ear. However, it has an effective volume of only 0,4 cm3, which is small enough not to produce significant resonances in the coupler in the frequency range below 16 kHz. Therefore, it will load the earphone with a known acoustic impedance, which allows repeatable measurements with low uncertainty to be obtained on earphones used in extended high-frequency audiometry.

PDF Catalog

PDF Pages PDF Title
2 undefined
4 European foreword
Endorsement notice
5 English
CONTENTS
7 FOREWORD
9 INTRODUCTION
10 1 Scope
2 Normative references
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
11 3.2 Abbreviated terms
4 Mechanical design of the 0,4 cm3 coupler
4.1 General
4.1.1 Overall design guidelines
12 4.1.2 Acceptance limits
4.2 Cavity dimensions
4.2.1 Critical dimensions
4.2.2 Effective coupler volume and cavity dimensions
4.3 Verification procedure of the effective coupler volume
4.4 Microphone
4.4.1 General
4.4.2 Microphone type
13 4.5 Static pressure equalisation vent
4.6 Acoustic transfer impedance level
5 Calibration
5.1 Reference environmental conditions
5.2 Method of calibration
Tables
Table 1 – The acoustic transfer impedance level modulus and the associated acceptance intervals
14 6 Coupling of receivers and hearing aids to the coupler
6.1 Coupling to a hearing aid receiver by means of tubing
6.2 Coupling to a hearing aid embedded in or connected to an earmould
Figures
Figure 1 – Coupling to a hearing aid receiver by means of coupling tubing
15 6.3 Coupling to a receiver in the canal (RIC)
Figure 2 – Coupling to an ITE, ITC, or CIC
16 6.4 Coupling to a BTE hearing aid with 2 mm continuous internal diameter tubing
Figure 3 – Coupling to a receiver in the canal (RIC)
17 6.5 Coupling to a BTE hearing aid with earmould simulator
Figure 4 – Coupling to a BTE hearing aid with 2 mmcontinuous internal diameter coupling tubing
18 6.6 Coupling to a BTE hearing aid with thin acoustic coupling tubing
Figure 5 – Coupling to a BTE hearing aid with earmould simulator
19 7 Maximum permitted expanded uncertainty for coupler conformance testing
Figure 6 – Coupling to a BTE hearing aid with thin coupling tubing
20 Figure 7 – Relationship between tolerance interval, corresponding acceptanceinterval and the maximum permitted uncertainty of measurement
Table 2 – Values of Umax for measurements
21 Annex A (informative)Example of a method for verification of the effective volume of the coupler
A.1 Method for verification of the effective volume of the coupler
22 A.2 Measurement uncertainty
Figure A.1 – Measurement setup for coupler volume measurement
Table A.1 – Typical components of measurement uncertaintyin the measurement of effective volume
23 Annex B (informative)Example of a method for the measurement of the acoustictransfer impedance of the 0,4 cm3 coupler
B.1 Measurement procedure
B.1.1 Acoustic transfer impedance
24 B.1.2 Setup for measuring the coupler acoustic transfer impedance
25 B.2 Typical coupler acoustic transfer impedance
Figure B.1 – Test set-up for measuring the coupler acoustic transfer impedance
Figure B.2 – Typical coupler acoustic transfer impedance
26 Figure B.3 – Typical acoustic transfer impedance times frequency
Table B.1 – Typical acoustic transfer impedance values
27 B.3 Measurement uncertainty
Table B.2 – Typical components of measurement uncertaintyin the measurement of acoustic transfer impedance
28 Annex C (informative)Example of one specific design of the coupler
Figure C.1 – Example of a specific design of the 0,4 cm3 coupler, shown with removable coupling plate with a nipple for the attachment of coupling tubing
29 Annex D (informative)Electrical analogue representation of the coupler as a tube model
Figure D.1 – Electrical analogue of the coupler as a lossytransmission line tube with lossy terminations
31 Table D.1 – List of constants
32 Figure D.2 – Transfer impedance model vs. measurements
Figure D.3 – Equivalent volume calculated from the model vs. measurements
33 Figure D.4 – Model predictions of coupler impedance
34 Annex E (informative)Example assessments of conformance to specifications of this document
E.1 General
E.2 Conformance criteria
E.3 Example test results
35 Table E.1 – Examples of assessment of conformance
36 Figure E.1 – Examples of assessment of conformance
37 Bibliography

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BS EN IEC 60318-8:2022
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