EN ISO 389-4:1998

SLOVENSKI STANDARD
01-november-1999
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Acoustics - Reference zero for the calibration of audiometric equipment - Part 4:
Reference levels for narrow-band masking noise (ISO 389-4:1994)
Akustik - Standard-Bezugspegel für die Kalibrierung audiometrischer Geräte - Teil 4:
Bezugspegel für schmalbandige Verdeckungsgeräusche (ISO 389-4:1994)
Acoustique - Zéro de référence pour l'étalonnage d'équipements audiométriques - Partie
4: Niveaux de référence pour bruit de masque en bande étroite (ISO 389-4:1994)
Ta slovenski standard je istoveten z: EN ISO 389-4:1998
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
ISO
STANDARD
389-4
First edition
1994-10-01
Acoustics - Reference zero for the
calibration of audiometric equipment -
Part 4:
Reference levels for narrow-band masking
nolse
Acoustique - Zero de rGf&ence pour I ’tStalonnage d ’equipements
a udiom6 triques -
Partie 4: Niveaux de r&f&ence pour bruit de masque en bande 6troite
Reference number
ISO 389-4:1994(E)
ISO 389-4: 1994(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide
federation of national Standards bodies (ISO member bodies). The work
of preparing International Standards is normally carried out through ISO
technical committees. Esch 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, governmental
and non-governmental, in liaison with ISO, also take part in the work. ISO
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 International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 389-4 was prepared by Technical Committee
ISO/TC 43, Acoustics.
This first edition of ISO 389-4 cancels and replaces ISO 8798:1987, of
which it constitutes a minor revision.
ISO 389 consists of the following Parts, under the general title Acoustics
- ßeference zero for the calibration of audiometric equipment:
- Part 7: ßeference equivalent threshold Sound pressure levels for
pure tones and supra-aural earphones
- Part 2: ßeferen ce equivalent thre shold Sound press ure levels
for
pure tones and insert earphones
- Part 3: ßeference equivalent threshold forte levels for pure tones
and bone Vibrators
- Part 4: ßeference levels for narrow-band masking noise
- Part 5: ßeference equivalent threshold Sound pressure levels for
pure tones in the frequency range 8 kHz to 16 kHz
- Part 6: ßeference equivalent threshold Sound pressure levels for
acoustic test Signals of short duration
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
0 ISO ISO 389-4: 1994(E)
- Part 7: Reference threshold of hearing under free-field and diffuse-
field lis tening conditions
Part 1 will be a re-issue of ISO 389:1991.
Annexes A and B of this part of ISO 389 are for information only.

0 ISO
ISO 389-4: 1994(E)
Introduction
ISO 389:1991 (to be re-issued as ISO 389-1) and ISO 389-2 specify the
reference zero for the calibration of pure-tone air-conduction audiometers.
ISO 389-3 specifies the corresponding data for pure-tone bone-conduction
audiometers.
For clinical diagnostic and other audiometric purposes, it is often necess-
at-y to prevent the test Signal being heard through the ear not being tested.
This masking is usually achieved by the presentation of a narrow band of
noise, the centre frequency of which coincides with the frequency of the
pure-tone Signal, and which is delivered by means of the ordinary supra-
aural or insert earphones of the audiometer.
IEC 645-1 specifies that masking levels for narrow-band noise be cali-
brated in terms of effective masking level and that the noise bandwidth
be between one-third and one-half of an octave.
The noise level required to just mask a pure tone of a given hearing level
has been calculated from known psychoacoustical data for ipsilateral
masking, i.e. when the tone to be masked and the masking noise are
presented through the Same earphone to the same ear.
In most audiometric applications the masking noise is, however, applied
by means of an earphone on the ear not being tested. The exact level of
the tone reaching that ear from the transducer on the test side is influ-
enced by skull attenuation and by the presence of the occlusion effect
from the masker earphone. These phenomena have to be considered with
regard to masking levels used in the audiometric procedure.

INTERNATIONAL STANDARD 0 ISO
ISO 389-4: 1994(E)
Acoustics - Reference zero for the calibration of
audiometric equipment -
Part 4:
Reference levels for narrow-band
maskina noise
ISO 389:1991, Acoustics - Standard reference zero
1 Scope
for the calibration of pure-tone air conduction
audiometers?
This patt of ISO 389 specifies reference leve Is for
narrow-band masking noise presented b)
/ air con-
ISO 389-2:1994, Acoustics - ßeference zero for the
duction from an earphone in pure-tone audiometry.
calibration of audiometric equipment - Part 2: Ref-
The data are given in terms of Ievels to be added to
erence equivalent threshold Sound pressure levels for
the reference equivalent threshold Sound pressure
pure tones and insert earphones.
levels for the corresponding pure-tone frequencies as
specified in ISO 389:1991 or ISO 389-2, respectively,
IEC 126:1973, IEC reference coupler for the
when the masking earphone is placed on the appro-
measurement of hearing aids using earphones coup-
priate acoustic coupler, ear Simulator or artificial ear.
led to the ear by means of ear inserts.
Data are given for noise bandwidths of one-third and
IEC 30311970, IEC provisional reference coupler for
one-half octaves.
the calibration of earphones used in audiometry.
NOTE 1 Som
...