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1、BRITISH STANDARD BS EN 60118-2:1996 BS 6083-2: 1996 Implementing Amendment No. 1, not published separately IEC 118-2: 1983 (including Amendments 1:1993 and 2:1997 to IEC 118-2:1983) Hearing aids Part 2: Methods for measurement of electroacoustical characteristics of hearing aids with automatic gain
2、control circuits The European Standard EN 60118-2:1995 with the inclusion of amendment A2:1997 has the status of a British Standard ICS 17.140.50 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 60118-2:1996 This British Standard, havin
3、g been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 September 1996 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference EPL/29 Draft for comment 84/
4、20636 DC ISBN 0 580 26160 3 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee EPL/29, Electroacoustics, upon which the following bodies were represented: British Association of Otolaryngologists British Hearing Aid Industry
5、 Association British Medical Association British Society of Audiology British Telecommunications plc Confederation of British Industry Department of Health Department of Trade and Industry (National Physical Laboratory) Health and Safety Executive Institute of Acoustics Institute of Sound and Vibrat
6、ion Research Institution of Electrical Engineers Medical Research Council Ministry of Defence Royal Aeronautical Society Royal National Institute for Deaf people Society of Environmental Engineers University of Exeter Amendments issued since publication Amd. No.DateComments 9753January 1998 Indicate
7、d by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 60118-2:1996 BSI 06-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 Text of EN 60118-25 List of referencesInside b
8、ack cover Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 60118-2:1996 ii BSI 06-1999 National foreword This British Standard has been prepared by Technical Committee EPL/29 and is the English language version of EN 60118-2:1996 Hearin
9、g aids Part 2: Hearing aids with automatic gain control circuits, including amendment A2:1997 published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC 118-2, second edition 1983, together with its Amendments 1:1993 and 2:1997, and supersedes BS 608
10、3-2:1984, which is withdrawn. From 1 January 1997, all IEC publications have the number 60000 added to the old number. For instance, IEC 27-1 has been renumbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers f
11、rom both systems. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references Public
12、ation referred toCorresponding British Standard EN 60118-0:1993 (IEC 118-0:1983) BS EN 60118 Hearing aids BS EN 60118-0:1993 Measurement of electroacoustical characteristics BS 6083 Hearing aids HD 450.1 S1:1984a (IEC 118-1:1983) Part 1:1984 Method for measurement of characteristics of hearing aids
13、with induction pick-up coil input HD 450.6 S1:1986 (IEC 118-6:1984) Part 6:1985 Specification for characteristics of electrical input circuits for hearing aids IEC 263:1982BS 6397:1983 Specification for scales and sizes for plotting frequency characteristics and polar diagrams IEC 268-8:1973BS 6840
14、Sound system equipment Part 8:1988 Methods for specifying and measuring the characteristics of automatic gain control devices a Superseded by EN 60118-1:1995 (IEC 118-1:1995), for which the corresponding British Standard is BS EN 60118-1:1995. Summary of pages This document comprises a front cover,
15、an inside front cover, pages i and ii, the EN title page, pages 2 to 18, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffi
16、eldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 60118-2 November 1995 + A2 July 1997 UDC 534.773.2:621.395.92:621.395.665:620.1:621.317.6Supersedes HD 450.2 S1:1984 Descriptors: Electromedical device, hearing
17、aid, automatic gain control, definitions, measurement procedures English version Hearing aids Part 2: Hearing aids with automatic gain control circuits (includes amendment A2:1997) (IEC 118-2:1983 + A1:1993 + A2:1997) Appareils de correction auditive Partie 2: Appareils de correction auditive compor
18、tant des commandes automatiques de gain (inclut lamendement A2:1997) (CEI 118-2:1983 + A1:1993 + A2:1997) Hrgerte Teil 2: Hrgerte mit automatischer Verstrkungsregelung (Enthlt nderung A2:1997) (IEC 118-2:1983 + A1:1993 + A2:1997) This European Standard was approved by CENELEC on 1994-03-08; amendmen
19、t A2 was approved by CENELEC on 1997-07-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concern
20、ing such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into it
21、s own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain,
22、 Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1995 Copyright reserved to CENELEC member
23、s Ref. No. EN 60118-2:1995 + A2:1997 E Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60118-2:1995 BSI 06-1999 2 Foreword The text of the International Standard IEC 118-2:1983, prepared by IEC TC 29, Electroacoustics, was approved by CEN
24、ELEC as HD 450.2 S1 on 1984-09-11. This Harmonization Document was submitted to the formal vote for conversion into a European Standard and was approved by CENELEC as EN 60118-2 on 1994-03-08. The text of amendment 1:1993 to the International Standard IEC 118-2:1983 was submitted to the formal vote
25、and was approved by CENELEC as amendment A1 to EN 60118-2 on 1994-03-08 without any modification. Having first withheld the publication of EN 60118-2 and its A1, the Technical Board of CENELEC has allowed on 1995-09-20 the circulation of the definitive version of EN 60118-2 with incorporation of its
26、 amendment A1. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, Annex ZA is normative. Annex ZA has been added by CENELEC. Foreword to amendment A2 The text of document 29/350/FDIS, future amendment 2 to IEC 60118-2:1983, prepared
27、 by IEC TC 29, Electroacoustics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as amendment A2 to EN 60118-2:1995 on 1997-07-01. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are give
28、n for information only. In this standard, Annex ZA is normative and Annex B and Annex C are informative. Annex ZA has been added by CENELEC. latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement(dop) 1996-07-01 latest d
29、ate by which the national standards conflicting with the European Standard have to be withdrawn(dow) 1996-07-01 latest date by which the amendment has to be implemented at national level by publication of an identical national standard or by endorsement(dop) 1998-04-01 latest date by which the natio
30、nal standards conflicting with the amendment have to be withdrawn(dow) 1998-04-01 Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60118-2:1995 BSI 06-19993 Contents Page Foreword2 1Scope5 2Object5 3Conditions5 4Explanation of terms5 4.1Au
31、tomatic gain control (AGC)5 4.2Steady-state input/output graph5 4.3Lower AGC limit or AGC threshold5 4.4Compression ratio (between specified input sound pressure level values)5 4.5Dynamic output characteristics5 4.6Attack time6 4.7Recovery time6 4.8AGC activated frequency response6 4.9Operating freq
32、uency range of the AGC6 4.10 Overall root-mean-square sound pressure level (overall r.m.s. SPL)6 4.11 One-third-octave band level6 4.12 Auto-spectrum (power spectrum)6 4.13 Cross-spectrum (GAB)6 4.14 Coherence6 4.15 Synchronous analysis6 5Steady-state input/output graph6 5.1Graph showing the relatio
33、n between input sound pressure level and output sound pressure level6 5.2Methods of measurement7 6Dynamic output characteristics7 6.1Characteristics to be measured7 6.2Methods of measurement7 7Non-linear distortion7 7.1Transients7 7.2Harmonic distortion7 7.3Intermodulation distortion7 8Effect on ste
34、ady-state and dynamic performance with respect to variation in battery or supply voltage8 9AGC activated frequency response of hearing aids with a single channel AGC circuit in operation using pure tone signals8 10Frequency response of hearing aids with AGC circuits in operation using steady-state b
35、road-band input signals9 Page Annex A (informative) Examples of measuring14 Annex B (informative) Smoothed data presentation16 Annex C (informative) Bibliography16 Annex ZA (normative) Normative references to international publications with their corresponding European publications17 Figure 1 Exampl
36、e of steady-state input/output graph12 Figure 2 Dynamic output characteristics of an AGC circuit13 Figure 3 Example of measuring system according to the comparison method employing two tracking bandpass filters14 Figure 4 Example of a measuring system employing digitally controlled input SPL and a b
37、and rejection filter15 Figure 5 Nominal values with upper and lower limits ( 2 dB) for one-third-octave band levels of the noise input signal at the test point15 Table 1 Nominal values for the one-third-octave band levels of the noise input signal at the test point11 Licensed Copy: sheffieldun sheff
38、ieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Thu Nov 09 03:59:26 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60118-2:1995 BSI 06-19995 1 Scope 1.1 This standard applies to the hearing aids of any type with automatic
39、gain control (AGC) circuits. This standard gives uniform methods for specifying dynamic and static performance characteristics of hearing aids with AGC circuits together with the relevant methods of measurement for these characteristics. This standard is confined to a description of the different ch
40、aracteristics and the relevant methods of measurement. It does not attempt to specify performance requirements. 1.2 This standard includes devices which have compression and/or limiting properties with respect to the envelope of the input signal. Devices which control the long-term average output le
41、vel are also included. a) AGC is employed to obtain compression, or the reduction of the dynamic range of the sound at the output, with the object of preserving the integrity of the input waveform. b) AGC circuits instead of clipping devices are often used for limiting purposes. A limiting effect oc
42、curs when the input/output characteristic flattens out at higher input levels. Limiting action is mainly used as a means of preventing excessive output sound from the hearing aid from reaching the listeners ear. 1.3 This standard does not include: a) Expanders. b) Clipping devices, which cut off the
43、 signal peaks above a certain level; such devices differ basically from AGC circuits, which, in a steady state, tend to preserve the waveform of the input signal. NOTEAn AGC circuit with very short recovery time may cause considerable distortion, especially in the low-frequency range. This should be
44、 given special attention. 2 Object 2.1 The purpose of this standard is to facilitate measurements of certain characteristics of hearing aids with AGC circuits that are not described elsewhere in IEC Publication 118-0: Hearing Aids, Part 0: Measurement of Electroacoustical Characteristics, and which
45、are considered necessary for a physical description of the function of the automatic gain control. 2.2 In general, the methods of measurement recommended are those which are considered to be the most directly related to the characteristics. This does not exclude the use of other stated methods which
46、 will give equivalent results. 3 Conditions 3.1 General conditions Reference is made to IEC Publication 268-8: Sound System Equipment, Part 8: Automatic Gain Control Devices. Measurements other than those described herein and that are stated in IEC Publication 118-0 can be performed in accordance wi
47、th that publication, but with AGC operating, provided the operating conditions are stated. 3.2 Throughout this standard, all sound pressure levels are referred to 20 4Pa. 4 Explanation of terms 4.1 Automatic gain control (AGC) A means in a hearing aid by which the gain is automatically controlled as
48、 a function of the magnitude of the envelope of the input signal or other signal parameter. NOTEThroughout this standard, reference is made to the use of acoustic inputs. However, where appropriate, additional measurements may be made with an electromagnetically induced input. 4.2 Steady-state input
49、/output graph The graph illustrating the output sound pressure level as a function of the input sound pressure level for a specified frequency, both expressed in decibels on identical linear scales (Figure 1, page 12). 4.3 Lower AGC limit or AGC threshold The input sound pressure level which, when applied to the hearing aid, gives a reduction in the gain of 2 0.5 dB with respect to the gain in the linear mode (Figure 1). 4.4 Compression ratio (between specified input sound pressure level values) Under steady-state conditions, the ratio of an