IEC 60118-0:2022

IEC 60118-0 ®
Edition 4.0 2022-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Hearing aids –
Part 0: Measurement of the performance characteristics of hearing aids

Électroacoustique – Appareils de correction auditive –
Partie 0: Mesure des caractéristiques fonctionnelles des appareils de correction
auditive
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IEC 60118-0 ®
Edition 4.0 2022-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Hearing aids –

Part 0: Measurement of the performance characteristics of hearing aids

Électroacoustique – Appareils de correction auditive –

Partie 0: Mesure des caractéristiques fonctionnelles des appareils de correction

auditive
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-5591-9

– 2 – IEC 60118-0:2022 © IEC 2022
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 General conditions. 15
4.1 Acoustic measurement method . 15
4.2 Acoustic couplers and occluded ear simulator . 15
4.3 Input signals and frequency range . 17
4.4 Reporting of data . 17
5 Test equipment . 17
5.1 General . 17
5.2 Test enclosure . 18
5.2.1 General . 18
5.2.2 Type 1 "anechoic-chamber" . 18
5.2.3 Type 2 "test-box" . 19
5.3 Measurement configuration . 19
5.3.1 General . 19
5.3.2 Measurement configuration for non-directional hearing aids . 19
5.3.3 Measurement configuration for directional hearing aids . 22
5.4 Sequential measurement method . 23
5.5 Other measurement methods . 24
5.6 Acoustic response measurement. 24
5.7 Sound source system . 24
5.8 Measurement system for the sound pressure level and distortion produced
by a hearing aid . 25
5.9 Electrical input . 26
5.10 Direct-current measurement system . 26
5.11 Magnetic field source for SPLIV measurements . 26
5.12 Magnetic field source for hearing aids having induction pick-up coil for use
with a telephone. 27
6 Normal operating conditions for a hearing aid . 27
6.1 General . 27
6.2 Battery or supply voltage . 28
6.3 Settings of controls . 28
6.3.1 General . 28
6.3.2 Full-on setting (FOS) . 28
6.3.3 Reference test setting (RTS) . 28
6.4 Ambient conditions. 29
6.5 Acoustical connection to the hearing aid . 29
6.6 Accessories . 29
7 Basic acoustic hearing aid measurements . 29
7.1 General . 29
7.2 Frequency response curves . 29
7.3 OSPL90 frequency response curve . 30
7.4 Full-on gain frequency response curve . 30
7.5 Basic frequency response curve . 31
7.5.1 Test procedure . 31

7.5.2 Frequency range of amplification . 31
7.5.3 Reference test gain (RTG) . 32
7.6 Total harmonic distortion . 32
8 Special hearing aid measurements . 33
8.1 General . 33
8.2 Difference frequency distortion . 33
8.2.1 Difference frequency distortion products . 33
8.2.2 Total difference frequency distortion . 35
8.3 Equivalent input noise (EIN) . 36
8.4 Equivalent input noise in one-third-octave bands (EIN-one-third-octave) . 37
8.5 Measurements of AGC hearing aids . 39
8.5.1 General . 39
8.5.2 Steady-state input-output characteristics . 39
8.5.3 AGC characteristics (attack and release time) . 40
8.6 Effects of tone control and gain control . 40
8.6.1 Basic frequency response: effect of tone control . 40
8.6.2 Frequency response: effect of gain control position . 40
8.6.3 Characteristics of the gain control . 41
8.7 Battery related measurements . 41
8.7.1 General . 41
8.7.2 Battery current measurement . 41
8.7.3 Effects of variation of battery or supply voltage and internal resistance . 41
9 Special measurements for hearing aids having non-acoustical inputs . 42
9.1 General . 42
9.2 Equivalence of output levels for a non-acoustical input . 43
9.3 Measurement setup for "Wireless" input (WL) . 43
9.3.1 General . 43
9.3.2 Measurement setup . 43
9.3.3 Wireless basic frequency response SPLWL . 44
9.3.4 HFA-SPLWL . 44
9.3.5 Frequency response with full-on setting . 44
9.3.6 Equivalent wireless input sensitivity level (EWLS) . 44
9.4 Hearing aids with electrical input . 45
9.4.1 General . 45
9.4.2 Basic frequency response (SPLEI) . 45
9.4.3 HFA-SPLEI . 45
9.4.4 Frequency response with full-on setting . 45
9.4.5 Equivalent electrical input sensitivity level (EEIS) . 45
9.4.6 Connector system for electrical input . 45
9.5 Hearing aids having induction pick-up coil in a vertical magnetic field . 46
9.5.1 General . 46
9.5.2 Basic frequency response in a vertical magnetic field (SPLIV) . 46
9.5.3 Frequency response with full-on setting (full-on SPLIV) . 46
9.5.4 Effect of gain control position on frequency response . 46
9.5.5 Harmonic distortion . 47
9.5.6 HFA-SPLIV . 47
9.5.7 Equivalent test loop sensitivity level (ETLS) . 47
9.5.8 Full-on HFA-SPLIV . 47
9.6 Hearing aids having induction pick-up coil for use with a telephone . 48

– 4 – IEC 60118-0:2022 © IEC 2022
9.6.1 SPLITS response curve . 48
9.6.2 HFA-SPLITS . 48
9.6.3 Relative simulated equivalent telephone sensitivity level (RSETS) . 49
10 Measurement of performance characteristics for production, supply and delivery
quality assurance purposes . 49
10.1 General . 49
10.2 Nominal characteristics . 49
10.3 Reference test gain . 50
10.4 OSPL90 . 50
10.5 Full-on gain . 50
10.6 Frequency response curve . 50
10.7 Bandwidth frequencies f and f . 51
1 2
10.8 Battery or supply voltage . 52
10.9 Battery current . 52
10.10 Total harmonic distortion . 52
10.11 Equivalent input noise level . 52
10.12 Full-on HFA-SPLIV . 53
10.13 Equivalent test loop sensitivity level (ETLS) . 53
10.14 Relative simulated equivalent telephone sensitivity level (RSETS) . 53
10.15 HFA-SPLITS . 53
10.16 Equivalent electrical input sensitivity level (EEIS) . 53
10.17 Steady-state input-output AGC characteristics . 54
10.18 Nominal attack time and release time . 54
11 Maximum permitted expanded uncertainty of measurements . 54
Annex A (normative) Simultaneous measurement method . 57
A.1 General . 57
A.2 Measurement method . 57
A.3 Comparison of the simultaneous method . 57
Annex B (normative) Substitution measurement method . 58
B.1 General . 58
B.2 Measurement method . 58
B.3 Comparison of the substitution method . 59
Annex C (normative) Effect of MLE on non-acoustic input hearing aids . 60
C.1 Acoustic and non-acoustic input equivalence . 60
C.2 In situ equivalence measurement in the case of a known MLE . 61
C.3 HFA equivalence of output levels for non-acoustical inputs . 62
C.3.1 General . 62
C.3.2 In situ output level equivalency of wireless input sensitivity level
(EWLS) . 63
C.3.3 In situ output level equivalency of electrical input sensitivity level (EEIS) . 63
C.3.4 In situ output level equivalency of test loop sensitivity level (ETLS) . 63
C.3.5 In situ output level equivalency of telephone sensitivity level (RSETS) . 64
Annex D (informative) Examples of uncertainty calculation . 65
D.1 General . 65
D.2 Uncertainty calculations . 65
D.3 Sound source system for test-box . 65
D.4 Sound source system for anechoic-chamber . 66
D.5 Hearing aid measurement . 67

3 3
Annex E (informative) Comparison of 2 cm coupler and 0,4 cm coupler . 68
E.1 General . 68
E.2 Influence of sound source impedance . 68
3 3
E.3 Comparison of frequency responses of the 0,4 cm , the 2 cm coupler and
the occluded ear simulator . 70
Bibliography . 72

Figure 1 – Example of test arrangement for behind the ear hearing aid . 21
Figure 2 – Example of test arrangement for in the ear hearing aid . 22
Figure 3 – Example of test arrangement for directional hearing aid . 23
Figure 4 – Telephone magnetic field simulator (TMFS) . 27
Figure 5 – Example of OSPL90 curve and basic frequency response curve. 30
Figure 6 – Example of determination of frequency range from basic frequency

response curve . 32
Figure 7 – Example of fundamental and difference frequency distortion products . 35
Figure 8 – Example of total difference frequency distortion . 36
Figure 9 – Example of hearing aid acoustic gain . 38
Figure 10 – Example of hearing aid output noise and test equipment noise . 38
Figure 11 – Example of hearing aid equivalent input noise and ambient noise . 39
Figure 12 – Example of a steady-state input-output characteristic . 40
Figure 13 – Measurement setup for wireless input . 44
Figure 14 – Example of hearing aids on TMFS for SPLITS test . 48
Figure 15 – Example of tolerance limits and determination of frequency range from
basic frequency response curve . 51
Figure 16 – Manufacturer acceptance interval (a) and purchaser acceptance interval
(b) with tolerance and maximum permitted uncertainty U . 56
max
Figure B.1 – Example of test arrangement for the substitution method . 59
Figure C.1 – Acoustic a) and non-acoustic b) transmission paths . 61
Figure C.2 – Example of SPLIV equivalence for ITC . 62
Figure E.1 – Deviation from the normalized coupler volume ratio as function of the
effective source volume V . 69
s
Figure E.2 – Magnitude frequency responses of acoustic impedance of the 2 cm , the
0,4 cm coupler and various hearing aid types . 70
3 3
Figure E.3 – Comparative measurement of the 0,4 cm coupler, the 2 cm coupler and
the occluded ear simulator frequency responses . 71

Table 1 – Overview on the use of acoustic couplers and occluded ear simulator . 17
Table 2 – Resistors and open circuit voltages for zinc-air battery simulators . 28
Table 3 – Distortion test frequencies and input sound pressure levels . 33
Table 4 – OSPL90: Acceptable deviation from the nominal values: . 50
Table 5 – Full-on gain: Acceptable deviation from the nominal value . 50
Table 6 – Tolerances and acceptance intervals of the frequency response . 51
Table 7 – Battery current: Acceptable deviation from the nominal value . 52
Table 8 – Total harmonic distortion: Acceptable deviation from the nominal value . 52

– 6 – IEC 60118-0:2022 © IEC 2022
Table 9 – Equivalent input noise level: Acceptable deviation from the nominal value . 52
Table 10 – Full-on HFA-SPLIV: Acceptable deviation from the nominal value. 53
Table 11 – ETLS: Acceptable deviation from the nominal value . 53
Table 12 – RSETS: Acceptable deviation from the nominal value . 53
Table 13 – HFA-SPLITS: Acceptable deviation from the nominal value . 53
Table 14 – EEIS: Acceptable deviation from the nominal value . 54
Table 15 – Acceptable deviation from the nominal values at input levels of 50 dB and
90 dB . 54
Table 16 – Values of U for measurements . 55
max
Table C.1 – HFA-MLE for various styles of hearing aids. 63
Table D.1 – Uncertainty sound source system for test-box . 66
Table D.2 – Uncertainty sound source system for anechoic-chamber . 66
Table D.3 – Uncertainty hearing aid measurement . 67

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROACOUSTICS –
HEARING AIDS –
Part 0: Measurement of the performance characteristics of hearing aids

FOREWORD
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 electrical and electronic fields. To this end and
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, 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 that 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.
IEC 60118-0 has been prepared by technical committee 29: Electroacoustics. It is an
International Standard.
This fourth edition merges and updates the methods previously described in IEC 60118-0:2015
and IEC 60118-7:2005. It cancels and replaces the third edition of IEC 60118-0 published in
2015. This edition constitutes a technical revision.
Measurements for quality control as described in IEC 60118-7:2005 can be found in Clause 10
of this document.
This edition includes the following significant technical changes with respect to previous
editions:
a) the default use of an acoustic coupler according to IEC 60318-5,
b) addition of the optional use of an occluded ear simulator according to IEC 60318-4,

– 8 – IEC 60118-0:2022 © IEC 2022
c) addition of the optional use of an acoustic coupler according to IEC 60318-8 (new standard
based on IEC TS 62886) when information about the response above 8 kHz is needed, or
the optional use of the acoustic coupler according to IEC 60318-8 for deep insert hearing
aids,
d) the addition of measurements of the performance of hearing aids for production, supply and
delivery quality assurance purposes,
e) corrected and updated measurement configuration and methods, adding the use of a
sequential measurement as preferred configuration,
f) updated and expanded measurement procedures for the non-acoustic inputs of the hearing
aid.
NOTE The substitution method described in Annex B has no relation to the substitution method described in
IEC 60118-0:2015.
The text of this International Standard is based on the following documents:
Draft Report on voting
29/1126/FDIS 29/1129/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 60118 series, published under the general title Electroacoustics –
Hearing aids, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
ELECTROACOUSTICS –
HEARING AIDS –
Part 0: Measurement of the performance characteristics of hearing aids

1 Scope
This part of IEC 60118 gives recommendations for the measurement of the performance
characteristics of air conduction hearing aids measured with an acoustic coupler or occluded
ear simulator.
This document is applicable to the measurement and evaluation of the electroacoustical
characteristics of hearing aids, for example for type testing and manufacturer data sheets.
This document is also applicable for the measurement of the performance characteristics of
hearing aids for production, supply and delivery quality-assurance purposes.
The measurement results obtained by the methods specified in this document will express the
performance under conditions of the measurement and can deviate substantially from the
performance of the hearing aid under actual conditions of use.
This document primarily uses an acoustic coupler according to IEC 60318-5 which is only
intended for loading a hearing aid with specified acoustic impedance and is not intended to
reproduce the sound pressure in a person's ear. For measurements reflecting the output level
in the normal human ear the occluded ear simulator according to IEC 60318-4 can be used. For
extended high-frequency measurements and for deep insert hearing aids, the acoustic coupler
according to IEC 60318-8 can be used.
This document also covers measurement of hearing aids with non-acoustic inputs, such as
wireless, inductive or electrical input.
This document does not cover the measurement of hearing aids for simulated in situ working
conditions, for which IEC 60118-8 can be applied.
This document does not cover the measurement of hearing aids under typical user settings and
using a speech-like signal, for which IEC 60118-15 can be applied.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60118-12, Hearing aids – Part 12: Dimensions of electrical connector systems
IEC 60318-4:2010, Electroacoustics – Simulators of human head and ear – Part 4: Occluded-
ear simulator for the measurement of earphones coupled to the ear by means of ear inserts
IEC 60318-5, Electroacoustics – Simulators of human head and ear – Part 5: 2 cm coupler for
the measurement of hearing aids and earphones coupled to the ear by means of ear inserts

– 10 – IEC 60118-0:2022 © IEC 2022
IEC 60318-8, Electroacoustics – Simulators of human head and ear – Part 8: Acoustic coupler
for high-frequency measurements of hearing aids and earphones coupled to the ear by means
of ear inserts
IEC 60268-2, Sound system equipment – Part 2: Explanation of general terms and calculation
methods
IEC 60263, Scales and sizes for plotting frequency characteristics and polar diagrams
IEC 61094-4, Measurement microphones – Part 4: Specifications for working standard
microphones
ISO 3, Preferred numbers – Series of preferred numbers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
SPL
sound pressure level
ten times the logarithm to the base 10 of the ratio of the square of the sound pressure, p, to the
square of a reference value, p , expressed in decibels, where the reference value, p , is 20 µPa
0 0
[SOURCE: ISO/TR 25417:2007, 2.2, modified – The abbreviated term has been added and the
formula and notes to entry have been omitted.]
3.2
hearing aid
wearable instrument intended to aid a person with impaired hearing
Note 1 to entry: A hearing aid usually consists of a microphone, amplifier, signal processor and earphone, powered
by a battery and possibly also containing alternative means of signal pickup such as induction coil, wireless input or
electrical input. It is fitted using audiometric and prescriptive methods.
Note 2 to entry: A hearing aid can be placed on the body (BW), behind the ear (BTE), in the ear (ITE, also named
full concha), in the canal (ITC), receiver in canal (RIC) or completely in the canal (CIC).
3.3
directional hearing aid
hearing aid for which the acoustic gain is dependent on the direction of sound incidence when
measured under free-field conditions
Note 1 to entry: Generally, a hearing aid with a single sound inlet port is non-directional and an aid with multiple
sound inlet ports is directional.
3.4
non-directional hearing aid
hearing aid for which the acoustic gain is independent of the direction of sound incidence when
measured under free-field conditions
Note 1 to entry: Generally, a hearing aid with a single sound inlet port is non-directional and an aid with multiple
sound inlet ports is directional.

3.5
gain control
manually or electronically operated control for the adjustment of the overall gain response
3.6
tone control
manually or electronically operated control for adjusting frequency dependent gain
3.7
vertical reference
line through or on a hearing aid which is vertical when the aid is positioned as worn on a head
and torso simulator (as per Figure C.1 in IEC 60118-8:2005) or, in the case of custom-made
hearing aids, as normally worn by the user
3.8
reference point
point related to the hearing aid sound inlet port(s) for the purpose of defining the position of the
hearing aid or wireless transmitter microphone
Note 1 to entry: For a hearing aid with one sound inlet port the reference point is at the sound inlet port. For a
hearing aid with two or more sound inlet ports the reference point is in the geometrical centre between the inlet ports.
3.9
test point
position in the test enclosure to which the measurements of the sound pressure level refer or
at which the strength of the magnetic field is determined and at which the reference point of the
hearing aid or wireless transmitter microphone is located for test purposes
3.10
test space
space which contains the test volume and the test point where the hearing aid or wireless
transmitter microphone is placed for testing
3.11
test volume
volume in the test space in which the sound field has the required conditions for testing
3.12
acoustic coupler
device for measuring the acoustic output of sound sources where the sound pressure is
measured by a calibrated microphone coupled to the source by a cavity of predetermined shape
and volume which does not necessarily approximate the acoustical impedance of the normal
human ear
3.13
ear simulator
device for measuring the acoustic output of sound sources where the sound pressure is
measured by a calibrated microphone coupled to the source so that the overall acoustic
impedance of the device approximates that of the normal human ear at a given location and in
a given frequency band
[SOURCE: IEC 60318-4:2010, 3.4]
3.14
input SPL
input sound pressure level
sound pressure level at the reference point of the hearing aid

– 12 – IEC 60118-0:2022 © IEC 2022
3.15
frequency response
sound pressure level measured in the acoustic coupler or ear simulator expressed as a function
of frequency under specified test conditions
3.16
basic frequency response curve
frequency response curve obtained at reference test setting with an input sound pressure level
of 60 dB
3.17
input-output characteristic
for a single frequency, a plot of the sound pressure level measured in the acoustic coupler or
ear simulator on the ordinate, against the sound pressure level applied to the hearing aid on
the abscissa, with equal decibel scale divisions on each axis
3.18
HFA
high-frequency average
average of gain or SPL in decibels at 1 000 Hz, 1 600 Hz and 2 500 Hz
3.19
special purpose hearing aid
hearing aid whose full-on gain at any frequency exceeds its full-on gain at 1 000 Hz, or at
1 600 Hz, or at 2 500 Hz by more than 15 dB
3.20
SPA
special purpose average
average of gain or SPL in decibels at the three one-third-octave-band frequencies each
separated by two-thirds of an octave, selected and stated by the manufacturer
Note 1 to entry: Throughout this document, wherever the term "high-frequency average" or "HFA" appears, "special-
purpose average" or "SPA" can be substituted for a special purpose hearing aid.
3.21
acoustic gain
at each test frequency, the difference in decibels obtained by subtracting the input SPL from
the SPL developed by the output from the hearing aid in the acoustic coupler or occluded ear
simulator
3.22
OSPL90
output SPL for 90 dB input SPL
SPL developed in the acoustic coupler or occluded ear simulator with an input SPL of 90 dB
with the hearing aid set to the full-on setting
Note 1 to entry: It is recognized that the maximum output level can occur with more, or occasionally with less, input
SPL than 90 dB. However, the differences are usually small over the frequency range of interest and the single input
SPL of 90 dB makes
...