HD 443 S1:1983

SLOVENSKI STANDARD
01-julij-2004
Occluded-ear simulator for the measurement of earphones coupled to the ear by
ear inserts
Occluded-ear simulator for the measurement of earphones coupled to the ear by ear
inserts
Simulator für den abgeschlossenen Gehörgang zur Messung an Horern, die mit
Ohreneinsätzen an das Ohr angekoppelt werden
Simulateur d'oreille occluse pour la mesure des écouteurs couplés à l'oreille par des
embouts
Ta slovenski standard je istoveten z: HD 443 S1:1983
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
17.140.50 Elektroakustika Electroacoustics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEI
NORME
IEC
INTERNATIONALE
INTERNATIONAL
Première édition
STANDARD
First edition
Simulateur d'oreille occluse pour la mesure
des écouteurs couplés à l'oreille par
des embouts
Occluded-ear simulator for the measurement
of earphones coupled to the ear by ear inserts
de reproduction réservés — Copyright — all rights reserved
© CEI 1981 Droits
Aucune partie de cette publication ne peut être reproduite ni No pa rt of this publication may be reproduced or utilized in
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711 © IEC 1981 - 3 -
CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
1. Scope 7
2. Object 7
3. Definitions 7
4. General requirements 9
Performance specifications 11
5.
6. Performance tests 15
7. Coupling arrangements 19
8. Calibration 19
9. Atmospheric reference conditions 19
FIGURES
APPENDIX A - Figure Al. - Example of one specific design of occluded-ear simulator . 24

711 © IEC 1981 - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
OCCLUDED-EAR SIMULATOR FOR THE MEASUREMENT
OF EARPHONES COUPLED TO THE EAR BY EAR INSERTS
FOREWORD
1) The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all the
rnational
National Committees having a special interest therein are represented, express, as nearly as possible, an inte
consensus of opinion on the subjects dealt with.
2) They have the form of recommendations for international use and they are accepted by the National Committees in that
sense.
rnational unification, the IEC expresses the wish that all National Committees should adopt the
3) In order to promote inte
text of the I EC recommendation for their national rules in so far as national conditions will permit. Any divergence
between the I EC recommendation and the corresponding national rules should, as far as possible, be clearly indicated in
the latter.
PREFACE
This standard has been prepared by Sub-Committee 29C: Measuring Devices, of IEC Technical
Committee No. 29: Electro-acoustics.
A first draft was discussed at the meeting held in Stockholm in 1979. As a result of this meeting, a
draft, Document 29C(Central Office)42, was submitted to the National Committees for approval
under the Six Months' Rule in October 1979.
The National Committees of the following countries voted explicitly in favour of publication:
Australia Netherlands
Belgium Norway
South Africa (Republic of)
China
Czechoslovakia Spain
Denmark Sweden
France Turkey
Germany Union of Soviet
Italy Socialist Republics
Other IEC publication quoted in this standard:
Publication No. 126: I EC Reference Coupler for the Measurement of Hearing Aids Using Earphones Coupled to the
Ear by Means of Ear Inse rts.
- 7 -
711 © IEC 1981
OCCLUDED-EAR SIMULATOR FOR THE MEASUREMENT
OF EARPHONES COUPLED TO THE EAR BY EAR INSERTS
Scope
1.
rt ear-
This standard specifies an occluded-ear simulator intended for the calibration of inse
phones in the frequency range 100 Hz to 10 000 Hz in terms of the sound pressure at the ear-
drum.
The occluded-ear simulator is also designed as the basis for a later extension intended to
simulate the complete ear canal for the calibration of earphones coupled to the ear by means
of open mould fittings or similar devices. A document for such a device is under considera-
tion.
2. Object
The occluded-ear simulator simulates the median values of relevant acoustical characteris-
tics of adult normal human ears.
The occluded-ear simulator does not simulate the leakage between an earmould and a
human ear canal; therefore, the results obtained with the simulator may deviate from the per-
rt earphone on a real ear, especially at low frequencies.
formance of an inse
riations among individual ears will occur and this should
Moreover, large performance va
be borne in mind when employing results obtained with the simulator.
Definitions
3.
For the purpose of this standard, the following definitions apply:
3.1 Ear insert
An ear insert is a device used to provide the acoustic coupling between an earphone and the
ear canal (e.g. an earmould or a similar device with or without a connecting tube).
Insert earphone
3.2
earphone is a small earphone coupled to the ear canal by means of an ear inse rt or
An insert
attached to a connecting element which is inserted into the ear canal. This ear inse rt may be a
part of the insert earphone.
3.3 Ear insert simulator
rt which terminates the entrance
An ear insert simulator (e.g. earmould simulator) is an inse
of the ear simulator and provides for passage of sound into the occluded-ear simulator
through an opening on its axis.

711 © IEC 1981 - 9 -
Ear simulator
3.4
An ear simulator is a device for measuring the output sound pressure of an earphone under
well-defined loading conditions in a specified frequency range. It consists essentially of a
principal cavity, acoustic load networks, and a calibrated microphone. The location of the
microphone is chosen so that the sound pressure at the microphone corresponds approxi-
mately to the sound pressure existing at the human eardrum.
3.5 Occluded-ear simulator
An occluded-ear simulator is an ear simulator which simulates the inner pa rt of the ear
canal, from the tip of an ear inse rt to the eardrum.
3.6 Reference plane
The reference plane of the occluded-ear simulator is a plane perpendicular to the axis of the
cavity of the simulator, chosen to pass through the position normally occupied by the tip of
the earmould.
3.7 Acoustic transfer impedance of the occluded-ear simulator
The acoustic transfer impedance of the occluded-ear simulator is the quotient of the sound
pressure at the diaphragm of its microphone by the volume velocity through the reference
plane.
4.
General requirements
4.1 Material and external dimensions
The occluded-ear simulator shall be constructed of non-magnetic and stable materials and
shall have sufficient mass to minimize response to vibration. The external dimensions of the
occluded-ear simulator shall be as small as possible to minimize the disturbance when the
simulator is inserted into a sound field.
4.2 Locating a calibrating transducer
The construction of the occluded-ear simulator shall permit the location of a transducer at
the reference plane for calibrating the simulator.
4.3 Microphone
The type of microphone shall be stated by the manufacturer of the occluded-ear simulator.
The pressure sensitivity level of the microphone shall be known within an accuracy of
±0.3 dB or better at 250 Hz. Relative to its value at 250 Hz, this level shall not vary by more
than ±0.5 dB in the frequency range 100 Hz to 5 kHz, and + 1.5 dB, –0.5 dB in the range
5 kHz to 10 kHz.
The acoustic impedance and the sensitivity of the microphone shall be stable.
Note. - The acoustic impedance of the microphone affects the overall acoustic impedance of the occluded-ear
simulator.
4.4
Pressure equalization
A vent provided to equalize the static pressure in the cavity of the occluded-ear simulator
shall have an acoustic resistance of 7 ± 5 GPa s/m3.

711 © IEC 1981 -11-
4.5 Principal cavity
The diameter of the principal cavity shall be 7.50 ± 0.02 mm.
4.6
Example of design
An example of one specific design of occluded-ear simulator is shown in Appendix A
(page 24).
5. Performance specifications
The performance specifications of the occluded-ear simulator with the microphone and the
acoustic networks in place shall apply for the atmospheric reference conditions given in
Clause 9.
5.1
Length of the principal cavity
The length of the principal cavity shall be such as to produce a half-wavelength resonance
at 14 ± 1 kHz.
5.2 Acoustic transfer impedance
The modulus of the acoustic transfer impedance and the associated tolerances shall be as
specified in Table I.
Notes 1. -
The tolerances have minimum values at the frequency 500 Hz, where the influence of leakage and wave
motion is small.
2. - At 500 Hz, the magnitude of the acoustic transfer impedance 35.9 ± 0.9 MPas/m
3 corresponds to the
magnitude of the effective volume of the ear simulator 1.26 ± 0.03 cm3.
3.
- The values of Table I are valid for the exact frequencies calculated from 1000 x 10 n/10, where n is a posi-
tive or negative integer or zero.

711 © IEC 1981 -13-
TABLE I
Modulus of the acoustic transfer impedance
and associated tolerances
Acoustic transfer
Nominal frequency impedance
in MPas/m3
(Hz) Modulus Tolerances
+10.3
100 173.4
-9.7
+8.3
125 140.3
-7.9
+6.5
160 109.6
-6.1
+4.2
200 88.7
-4.0
+3.3
250 71.0
-3.2
+2.7
56.3
-2.5
+2.1
44.9
-2.0
+0.9
500 35.9
-0.9
1.4
+
630 28.8
-1.3
1.1
+
800 23.0
-1.0
+
1.3
1 000
21.6
-1.2
+1.2
1 250 21.0
-1.2
+1.1
1 600 18.8
-1.1
+
1.2
2 000 16.3
-1.1
+
1.0
2 500 14.3
-1.0
+1.
...