1、Electroacoustics Hearing aids Method for measuring electroacoustic performance up to 16 kHz PD IEC/TS 62886:2016 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National foreword This Published Document is the UK implementation of IEC/TS 62886:2016. The UK participa
2、tion in its preparation was entrusted to Technical Committee EPL/29, Electroacoustics. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for
3、 its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 88484 9 ICS 17.140.50 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards
4、Policy and Strategy Committee on 30 September 2016. Amendments/corrigenda issued since publication Date Text affected PUBLISHED DOCUMENT PD IEC/TS 62886:2016 IEC TS 62886 Edition 1.0 2016-08 TECHNICAL SPECIFICATION Electroacoustics Hearing aids Method for measuring electroacoustic performance up to
5、16 kHz INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 17.140.50 ISBN 978-2-8322-3620-8 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colour inside PD IEC/TS 62886:2016 2 IEC TS 62886:2016 IEC
6、 2016 CONTENTS FOREWORD . 5 INTRODUCTION . 7 1 Scope 8 2 Normative references. 8 3 Terms, definitions and abbreviated terms . 8 3.1 Terms and definitions 8 3.2 Abbreviated terms . 9 4 Mechanical design of the 0,4 cm 3coupler 9 4.1 General . 9 4.2 Cavity dimensions . 10 4.2.1 Critical dimensions . 10
7、 4.2.2 Effective coupler volume 10 4.2.3 Diameter of the coupler cavity 11 4.3 Verification procedure of the effective coupler volume 11 4.3.1 General . 11 4.3.2 Test set-up 11 4.3.3 Effective volume of the coupler under test 11 4.4 Measuring microphone 12 4.4.1 General . 12 4.4.2 Preferred micropho
8、ne . 12 4.4.3 Alternative microphones . 12 4.5 Static pressure equalisation vent . 12 5 Calibration . 12 5.1 Reference environmental conditions 12 5.2 Calibration procedure 13 6 Coupling of receivers and hearing aids to the coupler . 13 6.1 Coupling to a hearing aid receiver by means of tubing . 13
9、6.2 Coupling to a hearing aid embedded in or connected to an earmould 13 6.3 Coupling to a receiver in the canal (RIC hearing aid) 14 6.4 Coupling to a BTE hearing aid with 2 mm continuous internal diameter tubing . 15 6.5 Coupling to a BTE hearing aid with earmould simulator 16 6.6 Coupling to a BT
10、E hearing aid with thin tubing . 17 7 Transfer impedance of the 0,4 cm 3coupler 18 8 Comparison of the 0,4 cm 3 , the 2 cm 3coupler and the occluded-ear simulator . 19 8.1 Sound pressure level frequency response curves . 19 8.2 Comparison of the coupler impedance with typical source impedances . 20
11、8.3 Influence of sound source impedance on measured level difference between the 0,4 cm 3coupler and the 2 cm 3coupler 21 9 Maximum permitted expanded uncertainty for coupler conformance testing . 22 10 Measurements using the 0,4 cm 3coupler . 23 10.1 General . 23 10.2 Test enclosure and test equipm
12、ent 23 10.3 Extended frequency range for total harmonic distortion measurements . 23 10.4 Presentation of data 24 10.4.1 General . 24 PD IEC/TS 62886:2016IEC TS 62886:2016 IEC 2016 3 10.4.2 Presentation as 0,4 cm 3coupler data . 24 10.4.3 Presentation as normalised to 2 cm 3coupler data 24 10.5 Maxi
13、mum permitted expanded uncertainty of measurements performed using the 0,4 cm 3coupler . 24 Annex A (informative) Response transforms between the 0,4 cm 3coupler and the occluded-ear simulator . 26 A.1 General . 26 A.2 Simulation model of the human ear and approximation of /2 resonances . 26 A.3 Mea
14、sured and simulated transform responses of a standard-fitting . 28 A.4 Transform curves for CIC-fitting and deep-insertion-fitting 29 Annex B (informative) Measurement and modelling of the transfer impedance of the 0,4 cm 3coupler . 33 B.1 Measurement procedure 33 B.1.1 Transfer impedance . 33 B.1.2
15、 Calibration of the volume velocity source at 250 Hz 33 B.1.3 Calibration of the volume velocity source over the frequency range from 100 Hz to 60 kHz . 34 B.1.4 Test set-up for measuring the coupler transfer impedance 34 B.2 Measurement of the coupler transfer impedance 35 B.3 Electrical analogue r
16、epresentation of the coupler as a tube model 38 Bibliography . 41 Figure 1 Mechanical design of the 0,4 cm 3coupler, shown with removable coupling plate with a nipple for the attachment of coupling tubing 10 Figure 2 Coupling to a hearing aid receiver by means of coupling tubing . 13 Figure 3 Coupli
17、ng to an ITE hearing aid 14 Figure 4 Coupling to a receiver in the canal (RIC hearing aid) . 15 Figure 5 Coupling to a BTE hearing aid with 2 mm continuous internal diameter tubing . 16 Figure 6 Coupling to a BTE hearing aid with earmould simulator . 17 Figure 7 Coupling to a BTE hearing aid with th
18、in coupling tubing 18 Figure 8 Magnitude frequency response of the transfer impedance frequency and the related equivalent volume 19 Figure 9 Comparative measurement of the 0,4 cm 3coupler, the 2 cm 3coupler and the occluded-ear simulator frequency responses . 20 Figure 10 Magnitude frequency respon
19、ses of acoustic impedance of the 2 cm 3 , the 0,4 cm 3coupler and various hearing aid types 21 Figure 11 Deviation from the normalized coupler volume ratio as a function of the effective volume of the sound source V s22 Figure A.1 Electrical analogue model of the human ear . 27 Figure A.2 Measured t
20、ransform response of a standard-fitting . 28 Figure A.3 Comparison between the measured and the simulated standard-fitting transform response . 29 Figure A.4 Transform responses for (a) standard-fitting, b) CIC-fitting and (c) deep- insertion-fitting 30 Figure B.1 Test set-up for measuring the coupl
21、er transfer impedance . 35 Figure B.2 Average frequency response of 8 coupler measurements . 35 Figure B.3 Average transfer impedance of the 0,4 cm 3coupler . 36 PD IEC/TS 62886:2016 4 IEC TS 62886:2016 IEC 2016 Figure B.4 Transfer impedance times frequency re 1 Pa/m 3 in dB and as equivalent volume
22、 in mm 3in the frequency range 100 Hz to 60 kHz . 36 Figure B.5 Electrical analogue model based on a tube model 39 Figure B.6 Comparison between the measured (solid line) and the simulated (dashed line) transfer impedance . 39 Figure B.7 Frequency responses of simulated 0,4 cm 3coupler input and tra
23、nsfer impedances 40 Table 1 Values of U maxfor basic measurements 23 Table 2 Distortion test frequencies and input sound pressure levels 24 Table 3 Values of U maxfor basic measurements 25 Table A.1 Transform data for standard-fitting (fitting at reference plane), CIC-fitting and deep-insertion-fitt
24、ing 31 Table B.1 Transfer impedance of the 0,4 cm 3coupler in the frequency range from 100 Hz to 60 kHz 37 PD IEC/TS 62886:2016IEC TS 62886:2016 IEC 2016 5 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ ELECTROACOUSTICS HEARING AIDS METHOD FOR MEASURING ELECTROACOUSTIC PERFORMANCE UP TO 16 kHz FOREWORD
25、 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electri
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34、use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility tha
35、t some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. The main task of IEC technical committees is to prepare International Standards. In exceptional circumstances, a technical committee ma
36、y propose the publication of a Technical Specification when the required support cannot be obtained for the publication of an International Standard, despite repeated efforts, or the subject is still under technical development or where, for any other reason, there is the future but no immediate pos
37、sibility of an agreement on an International Standard. Technical Specifications are subject to review within three years of publication to decide whether they can be transformed into International Standards. IEC TS 62886, which is a Technical Specification, has been prepared by IEC technical committ
38、ee 29: Electroacoustics. PD IEC/TS 62886:2016 6 IEC TS 62886:2016 IEC 2016 The text of this Technical Specification is based on the following documents: Enquiry draft Report on voting 29/897/DTS 29/902A/RVC Full information on the voting for the approval of this Technical Specification can be found
39、in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC website under “http:/webstore
40、.iec.ch“ in the data related to the specific publication. At this date, the publication will be transformed into an International standard, reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The colour i
41、nside logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. PD IEC/TS 62886:2016IEC TS 62886:2016 IEC 2016 7 INTRODUCTION Advanc
42、ement in hearing aid design makes it possible to increase the bandwidth of hearing aids up to 16 kHz. Accordingly, there is a need for an accurate and yet robust measurement method for the transducer (receiver, earphone) designer, the hearing aid designer, and the fitter of hearing aids. The 2 cm 3c
43、oupler as described in IEC 60318-5 is only suitable for measurements up to 8 kHz. The limitation is caused by unfavourable acoustic modes of the coupler. The occluded-ear simulator as described in IEC 60318-4 simulates the average human external ear up to 8 kHz, and can be used as a test coupler up
44、to 16 kHz. The occluded ear- simulator is designed for a specific insertion depth of the earmould, which is associated with a half-wavelength /2 resonance at about 13,5 kHz. This half-wavelength resonance degrades the reproducibility of measurement results in that frequency range and harmonic distor
45、tion measurements made at corresponding multiples of the resonance frequency. Also, this resonance represents a complex load to the hearing aid transducer, which makes it more difficult to differentiate between transducer and load related effects. The effective internal volume of the coupler describ
46、ed in this Technical Specification is 0,4 cm 3 , which is small enough not to produce any resonance in the frequency range below 16 kHz. The frequency response of the magnitude of acoustic impedance follows a pattern of a capacitive load up to about 30 kHz. With a sufficiently high source impedance
47、and a sufficiently small coupling volume, the 0,4 cm 3coupler produces an approximately 14 dB higher output at 1 kHz in comparison to data obtained with the 2 cm 3coupler. The coupler described in this document will allow the characterisation of hearing aids and transducers, including the verificati
48、on of simulation models, up to 16 kHz. 0,4 cm 3is also approximately the residual volume of the ear canal when fitted with a CIC hearing aid (completely-in-the-canal) hearing aid, making this coupler particularly useful for this application. In combination with an appropriate real-ear probe micropho
49、ne measurement, the 0,4 cm 3coupler will enable the derivation of real-ear to coupler difference (RECD) up to 16 kHz. PD IEC/TS 62886:2016 8 IEC TS 62886:2016 IEC 2016 ELECTROACOUSTICS HEARING AIDS METHOD FOR MEASURING ELECTROACOUSTIC PERFORMANCE UP TO 16 kHz 1 Scope IEC TS 62886, which is a Technical Specification, describes a coupler and measurement methods to characterise the electroacoustic performance of hearing aids and insert earpho
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