EN ISO 389:1995

SLOVENSKI STANDARD
SIST EN ISO 389:1999
01-november-1999
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Acoustics - Standard reference zero for the calibration of pure-tone air conduction
audiometers (ISO 389:1991)
Akustik - Standard-Bezugspegel für die Kalibrierung von Reinton-Luftleitungs-
Audiometern (ISO 389:1991)
Acoustique - Zéro normal de référence pour l'étalonnage des audiometres a sons purs
en conduction aérienne (ISO 389:1991)
Ta slovenski standard je istoveten z: EN ISO 389:1995
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
SIST EN ISO 389:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 389:1999

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SIST EN ISO 389:1999

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SIST EN ISO 389:1999

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SIST EN ISO 389:1999
IS0
I N TE R NAT1 O NA L
STANDARD
Third edition
1 99 1 -03-0 1
Acoustics - Standard reference zero for the
calibration of pure-tone air conduction
audiometers
Acoustique - Zéro normal de référence pour l'étalonnage des
audiomètres à sons purs en conduction aérienne
Reference number
ISO 3ag:iggi(~)

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SIST EN ISO 389:1999
IS0 389:1991 (E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Inter-
national Standard requires approval by at least 75% of the member
bodies casting a vote.
International Standard IS0 389 was prepared by Technical Committee
ISO/TC 43, Acoustics.
This third edition cancels and replaces the second edition (IS0
389:1985). It incorporates Addenda 1 (published in 1983) and 2 (pub-
lished in 1986).
Annexes A and B of this International Standard are for information only.
8 IS0 1991
Ali rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without
permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 CH-I21 1 Genève 20 Switzerland
Printed in Switzerland
ii

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SIST EN ISO 389:1999
IS0 389:1991 (E)
Introduction
The first edition of IS0 389 specified a standard reference zero for the
scale of hearing threshold level applicable to pure-tone air conduction
audiometers in terms of the response of certain models of earphone
measured on an artificial ear or coupler of stated type. Five of these
earphone-coupler combinations corresponded with those used at that
time in standardizing laboratories in France, Germany, the United
Kingdom, the USA and the USSR. In a second set of values the corre-
sponding reference equivalent threshold sound pressure levels
(RETSPL) for eleven audiometric earphones were given, referred to a
single type of coupler, the National Bureau of Standards, Washington,
USA, type SA coupler, which was later specified in IEC 303.
Most of the earphone-coupler combinations mentioned in the first edi-
tion of IS0 389 are now no longer in use. The IS0 member bodies of the
countries primarily concerned with those types of standard earphones
and artificial ears agreed to eliminate obsolete data. This was done in
the second edition of IS0 389. It contained only RETSPL values for two
earphone models still widely in use for audiometric purposes, namely
Telephonics type THD 39 with cushion type MX41/AR (or model 51) and
Beyer type DT 48, both in conjunction with an acoustic coupler comply-
ing with IEC 303.
The two remaining sets of data differ mainly as a consequence of dif-
ferences between the acoustical properties of the coupler and those of
the average human ear.
For the same reason, the RETSPL for an earphone of a model not cov-
ered by IS0 389 could not be inferred from the data given in that Inter-
national Standard. Until then it had been necessary to obtain the
appropriate values by subjective comparison with one of the specified
models of earphone.
In principle, RETSPL values would be rendered independent of earphone
model if they were referred to an artificial ear having acoustical prop-
erties exactly simulating those of the average human ear. A device de-
signed with this aim in view was standardized in 1971 in IEC 318.
Addendum 1 to IS0 389:1985 had therefore been prepared based on an
assessment of technical data provided by laboratories listed in
annex A on RETSPL values relative to the IEC artificial ear, covering a
variety of earphone models.
These data had been analysed to produce a set of RETSPL values which,
within an acceptable tolerance, provide a standard audiometric refer-
ence zero for earphones of any model within a broadly defined class. A
note on the derivation of the standard values and the origin of the data
input is given in annex A for information.
Use of the standard reference zero specified in Addendum 1 obviated
the need for subjective calibration of supra-aural audiometric earphones
which meet the broad requirements specified, and thus promoted
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SIST EN ISO 389:1999
IS0 389:1991(E)
agreement and uniformity in the expression of hearing threshold levels
throughout the world, without inhibiting the development of improved
models of supra-aural earphone.
The data of Addendum 1 are now incorporated in this third edition of
IS0 389.
In both IS0 389 and IS0 389/Add. 1, the RETSPL values were specified
for pure tones in octave steps from 125 Hz to 8000 Hz and for the inter-
mediate audiometric frequencies 1 500 Hz, 3 O00 Hz and 6 O00 Hz. How-
ever, in addition, 750 Hz is sometimes used as an intermediate
audiometric frequency, and Addendum 2 to IS0 389:1985 therefore
specified RETSPL values for that frequency.
Moreover, it had been considered desirable to harmonize intermediate
frequencies used in pure-tone audiometry with the preferred frequen-
cies in acoustics as specified in IS0 266. Addendum 2 therefore speci-
fied RETSPL values at all preferred frequencies in one-third octave steps
in the frequency range from 125 Hz to 8000 Hz. Details of the derivation
of the RETSPL values are given in annex A for further information. The
data of Addendum 2 are now also incoporated in this third edition of
IS0 389.
The RETSPL value specified at 750 Hz is intended for calibration of
audiometers providing pure tones of a fixed frequency of 750 Hz. The
other RETSPL values specified are primarily intended for calibration of
pure-tone audiometers having a continuously variable frequency, but
they may also be used in other applications, for example for establishing
reference levels for masking noise. The frequencies given in
IS0 389:1985 and Addendum 2 are consistent with the frequencies used
in IS0 7566 for the specification of the standard reference zero for the
calibration of bone conduction audiometers. Three sets of RETSPL val-
ues were specified. Two of these concern the same earphone models
as in IS0 389:1985. The third set of RETSPL values were specified for
supra-aural earphones other than those covered by IS0 389:1985 but
which fulfil the requirements specified in IS0 389/Add. 1.
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SIST EN ISO 389:1999
INTERNATIONAL STANDARD IS0 389:1991(E)
Acoustics - Standard reference zero for the calibration of
pure-tone air conduction audiometers
1 Scope 3 Definitions
This International Standard specifies a standard ref- For the purposes of this International Standard, the
erence zero for the scale of hearing threshold level fol lowi ng definitions apply.
i
applicable to pure-tone air conduction audiometers
in order to promote agreement and uniformity in the
3.1 air conduction: Transmission of sound through
expression of hearing threshold level measure-
the external and middle ear to the inner ear.
ments throughout the world.
3.2 acoustic coupler: A cavity of specified shape
It states the information in a form suitable for direct
and volume which is used for the calibration of a
application to the calibration of audiometers, that is,
supra-aural earphone in conjunction with a cali-
in terms of the response of two different standard
brated microphone to measure the sound pressure
on a coupler com-
models of earphone measured
developed within the cavity.
plying with IEC 303 and in terms of other supra-aural
earphones of models specified in 4.2 measured on
NOTE 1 An acoustic coupler is specified in IEC 303
an artificial ear complying with IEC 318.
It is based on an assessment of the information 3.3 artificial ear: A device for the calibration of ari
available from the various standardizing labora- earphone which presents to the earphone ari
tories responsible for audiometric standards and acoustic impedance equivalent to the impedance
from scientific publications. Some notes on the der- It is equipped
presented by the average human ear.
ivation and application of the recommended refer-
with a calibrated microphone for the measurement
ence levels are given in annex A.
of the sound pressure developed by the earphone.
NOTE 2 An artificial ear is specified in IEC 318.
3.4 threshold of hearing: The level of a sound at
2 Normative references
which, under specified conditions, a person gives
50 Yo of correct detection responses on repeated
The following standards contain provisions which,
trials.
through reference in this text, constitute provisions
of this International Standard. At the time of publi-
3.5 otologically normal person: A person in a
cation, the editions indicated were valid. All stan-
normal state of health who is free from all signs or
dards are subject to revision, and parties to
symptoms of ear disease and from obstructing wax
agreements based on this International Standard
in the ear canal, who has no history of undue expo-
are encouraged to investigate the possibility of ap-
sure to noise.
plying the most recent editions of the standards in-
dicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards. 3.6 equivalent threshold sound pressure level
(monaural earphone listening): For a given ear, at a
IEC 303:1970, IEC provisional reference coupler for
specified frequency, for a specified model of
the calibration of earphones used in audiometry.
earphone and for a stated force of application of the
earphone to the human ear, the sound pressure
IEC 318:1970, An IEC artificial ear, of the wideband level set up by the earphone in a specified acoustic
type, for the calibration of earphones used in coupler or artificial ear when the earphone is actu-
audiometry. ated by that voltage which, with the earphone ap-
1

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SIST EN ISO 389:1999
IS0 389:1991 (E)
plied to the ear concerned, would correspond to the
threshold of hearing.
Table 1 - Recommended reference equivalent
threshold sound pressure levels in a coupler com-
plying with IEC 303
3.7 reference equivalent threshold sound pressure
evels rounded to the nearest half decibel)
level (RETSPL): At a specified frequency, the modal
value of the equivalent threshold sound pressure
RETSPL
Frequency
(Reference: 20 IiPa)
levels of a sufficiently large number of ears of
otologically normal persons, of both sexes, aged
Hz
d0
between 18 and 30 years inclusive
...