SIST EN 60318-1:2010
(Main)Electroacoustics - Simulators of human head and ear - Part 1: Ear simulator for the calibration of supra-aural and circumaural earphones (IEC 60318-1:2009)
Electroacoustics - Simulators of human head and ear - Part 1: Ear simulator for the calibration of supra-aural and circumaural earphones (IEC 60318-1:2009)
This part of IEC 60318 specifies an ear simulator for the measurement of supra-aural and circumaural earphones (used for example in audiometry and telephonometry) applied to the ear without acoustical leakage, in the frequency range from 20 Hz to 10 kHz. The same device can be used as an acoustic coupler at additional frequencies up to 16 kHz.
Akustik - Simulatoren des menschlichen Kopfes und Ohres - Teil 1: Ohrsimulator zur Kalibrierung von supra-auralen und circumauralen Kopfhörern (IEC 60318-1:2009)
Electroacoustique - Simulateurs de tête et d'oreille humaines - Partie 1: Simulateur d'oreille pour la mesure des écouteurs supra-auraux et circumauraux (CEI 60318-1:2009)
La CEI 60318-1:2009 donne les spécifications d'un simulateur d'oreille pour la mesure des écouteurs supra-auraux et circumauraux (utilisés, par exemple, en audiométrie et téléphonométrie) appliqués sur l'oreille sans fuite acoustique, dans le domaine de fréquence compris entre 20 Hz et 10 kHz. Le même dispositif peut être utilisé en tant que coupleur acoustique à des fréquences supplémentaires allant jusqu'à 16 kHz. Cette deuxième édition annule et remplace la première édition parue en 1998 et remplace également la CEI 60318-2, publiée en 1998. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - une extension du domaine de fréquences à 16 kHz; - une spécification révisée pour l'impédance acoustique de transfert, y compris les tolérances; - une méthode pour la mesure de l'impédance acoustique de transfert; - des incertitudes de mesure élargies.
Elektroakustika - Simulatorji človeške glave in ušesa - 1. del: Simulator ušesa za kalibriranje nadušesnih in obušesnih slušalk (IEC 60318-1:2009)
Ta del IEC 60318 določa simulator ušesa za meritve nadušesnih in obušesnih slušalk (ki se na primer uporabljajo pri avdiometriji in telefonometriji), ki se uporabijo na ušesih brez uhajanja zvoka v frekvenčnem razponu med 20 Hz in 10 kHz. Isti pripomoček se lahko uporabi kot akustični spojnik pri dodatnih frekvencah do 16 kHz.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 60318-1:2010
01-marec-2010
1DGRPHãþD
SIST EN 60318-1:2002
(OHNWURDNXVWLND6LPXODWRUMLþORYHãNHJODYHLQXãHVDGHO 6LPXODWRUXãHVD]D
NDOLEULUDQMHQDGXãHVQLKLQREXãHVQLKVOXãDON ,(&
Electroacoustics - Simulators of human head and ear - Part 1: Ear simulator for the
calibration of supra-aural and circumaural earphones (IEC 60318-1:2009)
Akustik - Simulatoren des menschlichen Kopfes und Ohres - Teil 1: Ohrsimulator zur
Kalibrierung von supra-auralen und circumauralen Kopfhörern (IEC 60318-1:2009)
Electroacoustique - Simulateurs de tête et d'oreille humaines - Partie 1: Simulateur
d'oreille pour la mesure des écouteurs supra-auraux et circumauraux (CEI 60318-
1:2009)
Ta slovenski standard je istoveten z: EN 60318-1:2009
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
17.140.50 Elektroakustika Electroacoustics
SIST EN 60318-1:2010 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 60318-1:2010
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SIST EN 60318-1:2010
EUROPEAN STANDARD
EN 60318-1
NORME EUROPÉENNE
December 2009
EUROPÄISCHE NORM
ICS 17.140.50 Supersedes EN 60318-1:1998, EN 60318-2:1998
English version
Electroacoustics -
Simulators of human head and ear -
Part 1: Ear simulator for the measurement of supra-aural
and circumaural earphones
(IEC 60318-1:2009)
Electroacoustique - Akustik -
Simulateurs de tête et d'oreille humaines - Simulatoren des menschlichen Kopfes
Partie 1: Simulateur d'oreille und Ohres -
pour la mesure des écouteurs Teil 1: Ohrsimulator zur Kalibrierung
supra-auraux et circumauraux von supra-auralen und circumauralen
(CEI 60318-1:2009) Kopfhörern
(IEC 60318-1:2009)
This European Standard was approved by CENELEC on 2009-11-01. 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 concerning 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 its 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, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: Avenue Marnix 17, B - 1000 Brussels
© 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60318-1:2009 E
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SIST EN 60318-1:2010
EN 60318-1:2009 - 2 -
Foreword
The text of document 29/683/FDIS, future edition 2 of IEC 60318-1, prepared by IEC TC 29,
Electroacoustics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60318-1 on 2009-11-01.
This European Standard supersedes EN 60318-1:1998 and EN 60318-2:1998.
This European Standard includes the following significant technical changes with respect to
EN 60318-1:1998:
– an extension of the frequency range to 16 kHz;
– a revised specification for the acoustical transfer impedance, including tolerances;
– a method for measuring the acoustical transfer impedance;
– expanded measurement uncertainties.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2010-08-01
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2012-11-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60318-1:2009 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 61094-1 NOTE Harmonized as EN 61094-1:2000 (not modified).
IEC 61094-2 NOTE Harmonized as EN 61094-2:2009 (not modified).
IEC 61094-6 NOTE Harmonized as EN 61094-6:2005 (not modified).
ISO 389-1 NOTE Harmonized as EN ISO 389-1:2000 (not modified).
ISO 389-5 NOTE Harmonized as EN ISO 389-5:2005 (not modified).
ISO 389-8 NOTE Harmonized as EN ISO 389-8:2004 (not modified).
__________
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SIST EN 60318-1:2010
- 3 - EN 60318-1:2009
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application 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.
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year
1) 2)
IEC 61094-4 - Measurement microphones - EN 61094-4 1995
Part 4: Specifications for working standard
microphones
1)
ISO/IEC Guide 98-3 - Uncertainty of measurement - - -
Part 3: Guide to the expression of uncertainty
in measurement (GUM:1995)
1)
Undated reference.
2)
Valid edition at date of issue.
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SIST EN 60318-1:2010
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SIST EN 60318-1:2010
IEC 60318-1
®
Edition 2.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Simulators of human head and ear –
Part 1: Ear simulator for the measurement of supra-aural and circumaural
earphones
Electroacoustique – Simulateurs de tête et d'oreille humaines –
Partie 1: Simulateur d'oreille pour la mesure des écouteurs supra-auraux et
circumauraux
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
T
CODE PRIX
ICS 17.140.50 ISBN 2-8318-1059-6
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN 60318-1:2010
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CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references .6
3 Terms and definitions .6
4 Construction .7
4.1 General .7
4.2 Tolerances .9
4.3 Static pressure equalisation .10
4.4 Calibrated pressure-type microphone .10
4.5 Material .10
4.6 Measurement plane.11
4.7 Acoustic transfer impedance .11
5 Coupling of earphone to ear simulator .11
5.1 Supra-aural earphones .11
5.2 Circumaural earphones .11
6 Calibration.13
6.1 Reference environmental conditions.13
6.2 Method of calibration.13
7 Maximum permitted expanded uncertainty of measurements .13
Annex A (informative) Lumped-parameter electrical network analogue of the ear
simulator.15
Annex B (informative) Example of one specific design of ear simulator .17
Annex C (informative) Measurement method for the determination of the acoustical
transfer impedance of the ear simulator .21
Bibliography.25
Figure 1 – Schematic cross-section of the ear simulator configured for supra-aural
earphones .8
Figure 2 – Schematic cross-section of the ear simulator configured for circumaural
earphones .9
Figure A.1 – Analogue electrical network .15
Figure A.2 – Level of impedance modulus of the electrical analogue network.16
Figure A.3 – Phase of the impedance of the electrical analogue network .16
Figure B.1 – Example of one specific design of ear simulator.17
Figure B.2 – Adapter for use with circumaural earphones .18
Figure B.3 – Conical ring .19
Figure B.4 – Configuration when using the adapter and the conical ring .20
Figure C.1 – Key elements of measurement system.22
Figure C.2 – Transmitter microphone adapter to couple a transmitter microphone to the
ear simulator.23
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Table 1 – Specification for the acoustic transfer impedance level.12
Table 2 – Values of U for basic measurements .14
max
Table C.1 – Typical components of measurement uncertainty in the measurement of
acoustic transfer impedance .24
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROACOUSTICS –
SIMULATORS OF HUMAN HEAD AND EAR –
Part 1: Ear simulator for the measurement of supra-aural
and circumaural earphones
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 in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for 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
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
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
misinterpretation by any end user.
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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.
International Standard IEC 60318-1 has been prepared by IEC technical committee 29:
Electroacoustics.
This second edition cancels and replaces the first edition published in 1998 as well as
replacing IEC 60318-2, published in1998. It constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• an extension of the frequency range to 16 kHz;
• a revised specification for the acoustical transfer impedance, including tolerances;
• a method for measuring the acoustical transfer impedance;
• expanded measurement uncertainties.
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SIST EN 60318-1:2010
60318-1 © IEC:2009 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
29/683/FDIS 29/698/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 60318 series, under the general title Electroacoustics – Simulators of
human head and ear, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition; or
• amended.
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ELECTROACOUSTICS –
SIMULATORS OF HUMAN HEAD AND EAR –
Part 1: Ear simulator for the measurement of supra-aural
and circumaural earphones
1 Scope
This part of IEC 60318 specifies an ear simulator for the measurement of supra-aural and
circumaural earphones (used for example in audiometry and telephonometry) applied to the
ear without acoustical leakage, in the frequency range from 20 Hz to 10 kHz. The same
device can be used as an acoustic coupler at additional frequencies up to 16 kHz.
NOTE 1 This device has alternative configurations for supra-aural earphones and different types of circumaural
earphones. In practice, the alternative configurations can be realised through the use of adapters where necessary.
NOTE 2 Repeatability for supra-aural and circumaural earphones may get significantly worse above 10 kHz.
2 Normative references
The following referenced documents are indispensable for the application 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 61094-4, Measurement microphones – Part 4: Specifications for working standard
microphones
ISO/IEC Guide 98-3, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM: 1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
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
3.2
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
3.3
supra-aural earphone
earphone applied externally to the outer ear and intended to rest on the pinna
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SIST EN 60318-1:2010
60318-1 © IEC:2009 – 7 –
3.4
circumaural earphone
earphone which encloses the pinna and rests on the surrounding surface of the head
NOTE Contact with the head is normally maintained by compliant cushions. Circumaural earphones may touch but
not significantly compress the pinna.
3.5
acoustic impedance
at a specified surface, quotient of the sound pressure by volume velocity through the surface
–3
NOTE Unit: Pa·s·m .
3.6
acoustic transfer impedance of the ear simulator
quotient of the sound pressure acting on the diaphragm of the microphone by volume velocity
through the planar surface bounded by the upper rim of the ear simulator
–3
NOTE Unit: Pa·s·m .
3.7
level of acoustic transfer impedance
ten times the logarithm to the base of ten of the quotient of the absolute value (modulus) of
the squared acoustic transfer impedance of the ear simulator by the squared reference
–3
acoustic transfer impedance of one pascal second per cubic meter (Pa·s·m )
NOTE Unit: decibel (dB).
4 Construction
4.1 General
The measurements of supra-aural and circumaural earphones each require the ear simulator
to have a different external configuration. Apart from this, the remaining specifications apply
to both types of earphone.
For supra-aural earphones the coupling surface of the ear simulator has sloped sides to
match the shape of the earphone cushions. For circumaural earphones, a flat coupling
surface is specified to suit the variety of earphone designs that may be encountered. Figure 1
shows the ear simulator configuration for supra-aural earphones and Figure 2 shows that for
circumaural earphones.
Internally, the ear simulator is composed of three acoustically coupled cavities. The primary
cavity is conical in shape and houses the microphone at its lower surface. The key
dimensions of the primary cavity and the acoustical compliances of each cavity are specified
in Figure 1 (and replicated in Figure 2). The secondary cavities are coupled to the primary
cavity by elements having acoustical mass and resistance. The lumped-parameter values of
the coupling elements shall be as follows:
2 2 –3
M = 4,5 × 10 Pa·s ·m
a2
4 2 –3
M = 1,06 × 10 Pa·s ·m
a3
6 –3
R = 6,05 × 10 Pa·s·m
a2
7 -3
R = 2 × 10 Pa·s·m
a3
M and M represent acoustic masses, R and R represent acoustic resistances. These
a2 a3 a2 a3
values are applicable for the reference environment conditions and are subject to the
tolerances of 4.2.
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A pressure equalization mechanism (R ) is included.
a1
An electrical analogue of the ear simulator is given in Annex A.
The general construction of the ear simulator and mounting of the microphone shall aim to
reduce the response to vibration of any earphone or to sound outside the cavity.
Dimensions in millimeters
∅25
56,5° ± 0,5°
32°
R
a1
V
1
–11 3 –1
C = 1,85 × 10 m ⋅Pa
a1
M M
a2 a3
R R
a2 ∅13,2 a3
V V
2 3
–11 3 –1 –11 3 –1
C = 1,43 × 10 m ⋅Pa C = 5,28 × 10 m ⋅Pa
a2 a3
1
IEC 1654/09
Key
1 microphone
NOTE 1 The volume of cavity V includes the total effective volume of the microphone capsule, a corresponding
1
correction for the presence of a protective grid also being taken into account.
NOTE 2 The acoustical compliance of the cavities may depend on the shape as well as the volume.
NOTE 3 Tolerances on dimensions are specified in 4.2.
Figure 1 – Schematic cross-section of the ear simulator configured
for supra-aural earphones
An ear simulator only capable of having the configuration shown in Figure 1, but meeting all
other specifications in this standard shall be considered as conforming to this part of
IEC 60318 for supra-aural earphones only.
h = 8,26
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SIST EN 60318-1:2010
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Dimensions in millimeters
∅25
56,5° ± 0,5°
2
32°
R
a1
V
1
–11 3 –1
C = 1,85 × 10 m ⋅Pa
a1
M M
a2 a3
R R
a2 a3
∅13,2
V V
2 3
–11 3 –1 –11 3 –1
C = 1,43 × 10 m ⋅Pa C = 5,28 × 10 m ⋅Pa
a2 a3
1
IEC 1655/09
Key
1 microphone
2 flat coupling surface
NOTE 1 The external face of the flat surface should be marked with a series of rings concentric with the opening
in the ear simulator to aid alignment of the earphone.
NOTE 2 The 0,8 mm lip at the entrance to the ear simulator is an artefact of a typical practical realisation of this
configuration, where a flat plate adapter is inserted between the body of the ear simulator and a removable conical
ring (see Annex B for details).
NOTE 3 Tolerances on dimensions are specified in 4.2.
Figure 2 – Schematic cross-section of the ear simulator configured
for circumaural earphones
The dimensions of the flat coupling surface are not critical, but shall be sized to accommodate
the range of circumaural earphones to be measured (together with their headbands. if
appropriate), noting that these are often non-circular. A size of approximately 100 mm ×
120 mm is appropriate.
An ear simulator only capable of having the configuration shown in Figure 2, but meeting all
other specifications in this standard shall be considered as conforming to this part of
IEC 60318 for circumaural earphones only.
An example of a design of the ear simulator, including the adapter to convert from supra-aural
to circumaural configuration, is shown in Annex B.
4.2 Tolerances
The following specified tolerances are for manufacturing the ear simulator and are not
normally subject to checking by a test laboratory. The specified dimensions determine the
acoustic transfer impedance of the device, which can be tested for conformance (see 4.7).
The distance h between a plane through the upper rim of the ear simulator and the diaphragm
of the microphone shall be 8,26 mm ± 0,30 mm.
h = 8,26
0,8
5,4
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Other specified linear dimensions shall have a tolerance of ± 0,3 mm.
The angular dimensions 56,5° shall have a tolerance of ± 0,5°.
+3 °
The angular dimension 32° shall have a tolerance of .
−1°
The acoustical compliances, masses and resistances shall each have a tolerance of ± 10 %.
4.3 Static pressure equalization
Any change in the static pressure within the ear simulator caused by assembly of the
earphone to the cavity and microphone shall decay toward the static ambient pressure with a
time constant less than 1,5 s. If this necessitates the introduction of a controlled leak in the
ear simulator, it shall have the following characteristics:
3
;
a) it shall not alter the total cavity volume by more than 20 mm
b) it shall attenuate external sound reaching the cavity, with the entrance blocked, by at least
16 dB at 100 Hz, increasing by 6 dB per octave for increasing frequency.
NOTE 1 This specification for the static pressure equalization is equivalent to a value for R of nominally 500 ×
a1
6 –3
10 Pa⋅s⋅m .
NOTE 2 Equalization can be realised, for example, by a capillary tube with a diameter of 0,3 mm and a length of
9 mm.
4.4 Calibrated pressure-type microphone
A calibrated microphone is located at the base of cavity V . The acoustic impedance of the
1
3
microphone diaphragm shall be high, so that the equivalent volume is less than 20 mm over
the specified range of frequencies.
In the frequency range from 20 Hz to 10 kHz, the overall pressure sensitivity level of the
microphone and associated measuring system shall be known with an uncertainty not
exceeding 0,2 dB for a level of confidence of 95 %. The microphone shall be coupled to the
cavity V with a protective grid and without leakage. The microphone shall conform to the
1
requirements of IEC 61094-4 for a type WS2P microphone.
For measurements above 10 kHz the overall pressure sensitivity level of the microphone and
associated measuring system over the specified frequency range shall be known with an
uncertainty not exceeding 0,5 dB for a level of confidence of 95 %. Furthermore there shall be
no protection grid or other obstruction between the microphone diaphragm and cavity V .
1
The make and model of the microphone shall be specified, together with any adapter used.
NOTE 1 The obstruction caused by the protection grid may cause the sound pressure acting on the microphone
diaphragm to be non-uniform.
1
NOTE 2 A microphone conforming with the requirements of IEC 61094-1 [1] for a type LS2aP microphone
provides a suitable configuration for use above 10 kHz. For some models of type WS2P microphone the
manufacturer supplies an ring to be used in place of the grid, that enables the microphone to be converted to type
LS2aP.
4.5 Material
The ear simulator and the adapters shall be made of a material that has no negative
influences on its performance. For example it should be acoustically hard and dimensionally
stable.
———————
1
Figures in brackets refer to the bibliography.
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4.6 Measurement plane
The plane of the microphone diaphragm shall be understood to represent the entrance of the
mean human ear canal, up to 10 kHz. Beyond this frequency, the device can only be
considered as an acoustic coupler having no direct relation to the mean human ear canal.
4.7 Acoustic transfer impedance
In the frequency range below 10 kHz, the ear simulator is designed so that its acoustic
transfer impedance matches the input impedance of the average human ear under sealed
conditions. Under reference environmental conditions, the ear simulator shall couple an
applied earphone to the microphone with an acoustic transfer impedance given in Table 1.
The tolerance on the frequency specified in Table 1 is 0,1 %.
NOTE 1 The acoustic transfer impedance is specified, because for practical reasons the locations of the earphone
and microphone are physically separated within the ear simulator. By modelling the acoustic input impedance of
real ears with the acoustic transfer impedance of the ear simulator, the sound pressure measured by the
microphone represents the sound pressure applied to the entrance of the ear canal.
NOTE 2 The acoustic impedance of an applied earphone will add in p
...
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