SIST EN ISO 4869-1:2019
(Main)Acoustics - Hearing protectors - Part 1: Subjective method for the measurement of sound attenuation (ISO 4869-1:2018)
Acoustics - Hearing protectors - Part 1: Subjective method for the measurement of sound attenuation (ISO 4869-1:2018)
This document specifies a subjective method for measuring sound attenuation of hearing protectors
at the threshold of hearing. The method is a laboratory method designed to yield reproducible values
under controlled measurement conditions. The values reflect the attenuating characteristics of the
hearing protector only to the extent that users wear the device in the same manner as did the test
subjects.
For a more representative indication of field performance the methods of ISO/TS 4869-5 can be used.
This test method yields data which are collected at low sound pressure levels (close to the threshold
of hearing) but which are also representative of the attenuation values of hearing protectors at higher
sound pressure levels. An exception occurs in the case of amplitude-sensitive hearing protectors for
sound pressure levels above the point at which their level-dependent characteristics become effective.
At those sound pressure levels the method specified in this document is inapplicable, as it will usually
underestimate sound attenuation for these devices.
NOTE Due to masking from physiological noise in the occluded ear tests, sound attenuations below 500 Hz
can be overestimated by a few decibels.
Akustik - Gehörschützer - Teil 1: Subjektive Methode zur Messung der Schalldämmung (ISO 4869-1:2018)
Dieses Dokument legt ein subjektives Verfahren zur Messung der Schalldämmung von Gehörschützern an der Hörschwelle fest. Das Verfahren ist ein Laborverfahren, das dafür ausgelegt ist, unter kontrollierten Messbedingungen reproduzierbare Werte zu ergeben. Die Werte reflektieren die Schalldämmeigenschaften des Gehörschützers nur insoweit, als die Benutzer ihn in der gleichen Weise tragen wie die Versuchs¬personen.
Für eine repräsentativere Angabe der Leistung in der Praxis können die Verfahren nach ISO/TS 4869 5 angewendet werden.
Dieses Prüfverfahren liefert Daten, die bei niedrigen Schalldruckpegeln (in der Nähe der Hörschwelle) ermit¬telt werden, die jedoch auch repräsentativ für die Schalldämmwerte der Gehörschützer bei höheren Schall¬druckpegeln sind. Eine Ausnahme bilden amplitudenempfindlicheN1) Gehörschützer für Schalldruckpegel, die oberhalb des Einsatzpunktes ihrer pegelabhängigen Charakteristik liegen. Bei derartigen Schalldruckpegeln ist das im vorliegenden Dokument festgelegte Verfahren nicht anwendbar, weil es üblicherweise zu einer Unter¬schätzung der Schalldämmung dieser Gehörschützer führt.
ANMERKUNG Aufgrund der in den Versuchen mit aufgesetztem Gehörschützer auftretenden Maskierung durch physiologische Geräusche können Schalldämmungen unterhalb von 500 Hz um einige Dezibel überschätzt werden.
Acoustique - Protecteurs individuels contre le bruit - Partie 1: Méthode subjective de mesurage de l'affaiblissement acoustique (ISO 4869-1:2018)
Le présent document spécifie une méthode subjective de mesurage de l'affaiblissement acoustique apporté par des protecteurs individuels contre le bruit au seuil d'audition. Il s'agit d'une méthode de laboratoire conçue pour obtenir des valeurs reproductibles dans des conditions de mesurage contrôlées. Ces valeurs ne reflètent les caractéristiques d'affaiblissement du protecteur individuel contre le bruit que dans la mesure où les utilisateurs le portent de la même façon que les sujets lors des essais.
Pour une indication plus représentative de la performance in situ, les méthodes de l'ISO/TS 4869‑5 peuvent être utilisées.
Avec la méthode d'essai décrite, les données sont obtenues à des niveaux de pression acoustique bas (proches du seuil d'audition), mais sont également représentatives des valeurs de l'affaiblissement apporté par les protecteurs individuels contre le bruit à des niveaux de pression acoustique plus élevés, sauf, dans le cas des protecteurs individuels contre le bruit à atténuation dépendante du niveau, lorsque les niveaux de pression acoustique sont supérieurs au seuil au-delà duquel la dépendance du niveau devient effective. À ces niveaux de pression acoustique, la méthode spécifiée par le présent document devient inapplicable car elle conduit habituellement à une sous-estimation de l'affaiblissement apporté par ces dispositifs.
NOTE En raison de l'effet de masque dû au bruit physiologique lors des essais oreilles occluses, les affaiblissements acoustique au-dessous de 500 Hz peuvent être surestimés de quelques décibels.
Akustika - Oprema za varovanje sluha - 1. del: Subjektivna metoda za merjenje dušenja zvoka (ISO 4869-1:2018)
Ta dokument določa subjektivno metodo za merjenje dušenja zvoka pri opremi za varovanje sluha pri pragu slišnosti. Metoda je laboratorijska metoda, katere namen je doseči ponovljive vrednosti pod nadzorovanimi pogoji merjenja. Vrednosti odražajo lastnosti dušenja opreme za varovanje sluha samo v obsegu, v katerem uporabniki opremo uporabljajo na enak način kot osebe, ki so sodelovale pri preskušanju.
Za bolj reprezentativen kazalnik terenske zmogljivosti je mogoče uporabiti metode iz standarda ISO/TS 4869-5. Rezultat te metode so podatki, ki so zbrani pri nizkih ravneh zvočnega tlaka (blizu praga slišnosti), vendar so reprezentativni tudi za vrednosti dušenja opreme za varovanje sluha pri višjih ravneh zvočnega tlaka. Izjema se pojavi pri opremi za varovanje sluha, občutljivi na spremembe amplitude, in sicer za ravni zvočnega tlaka nad točko, pri kateri njene lastnosti, odvisne od ravni, začnejo učinkovati.
Pri teh ravneh zvočnega tlaka se metoda, opredeljena v tem dokumentu, ne uporablja, saj običajno podceni dušenje zvoka te opreme.
OPOMBA: Zaradi maskiranja fiziološkega šuma pri preskusih s pokritimi ušesi se lahko dušenje zvoka pod 500 Hz preceni za nekaj decibelov.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 4869-1:2019
01-januar-2019
1DGRPHãþD
SIST EN 24869-1:1999
Akustika - Oprema za varovanje sluha - 1. del: Subjektivna metoda za merjenje
dušenja zvoka (ISO 4869-1:2018)
Acoustics - Hearing protectors - Part 1: Subjective method for the measurement of sound
attenuation (ISO 4869-1:2018)
Akustik - Gehörschützer - Teil 1: Subjektive Methode zur Messung der Schalldämmung
(ISO 4869-1:2018)
Acoustique - Protecteurs individuels contre le bruit - Partie 1: Méthode subjective de
mesurage de l'affaiblissement acoustique (ISO 4869-1:2018)
Ta slovenski standard je istoveten z: EN ISO 4869-1:2018
ICS:
13.340.20 Varovalna oprema za glavo Head protective equipment
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
SIST EN ISO 4869-1:2019 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 4869-1:2019
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SIST EN ISO 4869-1:2019
EN ISO 4869-1
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2018
EUROPÄISCHE NORM
ICS 13.340.20 Supersedes EN 24869-1:1992
English Version
Acoustics - Hearing protectors - Part 1: Subjective method
for the measurement of sound attenuation (ISO 4869-
1:2018)
Acoustique - Protecteurs individuels contre le bruit - Akustik - Gehörschützer - Teil 1: Subjektive Methode
Partie 1: Méthode subjective de mesurage de zur Messung der Schalldämmung (ISO 4869-1:2018)
l'affaiblissement acoustique (ISO 4869-1:2018)
This European Standard was approved by CEN on 23 April 2018.
CEN 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 CEN-CENELEC Management Centre or to any CEN
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 CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4869-1:2018 E
worldwide for CEN national Members.
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SIST EN ISO 4869-1:2019
EN ISO 4869-1:2018 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 4869-1:2019
EN ISO 4869-1:2018 (E)
European foreword
This document (EN ISO 4869-1:2018) has been prepared by Technical Committee ISO/TC 43
"Acoustics" in collaboration with Technical Committee CEN/TC 211 “Acoustics” the secretariat of which
is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by May 2019, and conflicting national standards shall be
withdrawn at the latest by May 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 24869-1:1992.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4869-1:2018 has been approved by CEN as EN ISO 4869-1:2018 without any
modification.
3
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SIST EN ISO 4869-1:2019
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SIST EN ISO 4869-1:2019
INTERNATIONAL ISO
STANDARD 4869-1
Second edition
2018-10
Acoustics — Hearing protectors —
Part 1:
Subjective method for the
measurement of sound attenuation
Acoustique — Protecteurs individuels contre le bruit —
Partie 1: Méthode subjective de mesurage de l'affaiblissement
acoustique
Reference number
ISO 4869-1:2018(E)
©
ISO 2018
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SIST EN ISO 4869-1:2019
ISO 4869-1:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 4869-1:2019
ISO 4869-1:2018(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measurement of the sound attenuation of hearing protectors . 3
4.1 Test signals . 3
4.2 Test site . 3
4.2.1 General. 3
4.2.2 Sound pressure level and sound pressure level variation . 3
4.2.3 Reverberation time . 4
4.2.4 Ambient noise level . 4
4.3 Test equipment . 5
4.4 Test subjects . 6
4.5 General test procedure and instruction of the test subject . 6
4.6 Determination of hearing protector attenuation . 7
5 Application force . 8
5.1 Earmuffs. 8
5.2 Semi-aural earplugs . 8
6 Test report . 8
Annex A (normative) Uncertainty of hearing protector attenuation measurements .10
Annex B (informative) Evaluation of two hearing protector attenuation measurements .14
Annex C (informative) Minimum and maximum sound pressure levels for test signals .17
Bibliography .18
© ISO 2018 – All rights reserved iii
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SIST EN ISO 4869-1:2019
ISO 4869-1:2018(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. 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, 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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This second edition cancels and replaces the first edition (ISO 4869-1:1990), which has been technically
revised.
The main changes compared to the previous edition are as follows:
The revision includes changes mainly of the sound field requirements, specification of test equipment,
test procedures and instructions to the test subjects, and uncertainty of the measurements. The sound
field requirements are based on published and unpublished laboratory experience, especially [10] and
[11] in the Bibliography.
A list of all parts in the ISO 4869 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved
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SIST EN ISO 4869-1:2019
ISO 4869-1:2018(E)
Introduction
Hearing protectors are commonly used to reduce the noise to which the ear is exposed. Hearing
protectors are manufactured as earplugs, earmuffs or helmets. A standardized method of sound
attenuation measurement allows comparison of performance data obtained in different locations under
similar conditions.
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SIST EN ISO 4869-1:2019
INTERNATIONAL STANDARD ISO 4869-1:2018(E)
Acoustics — Hearing protectors —
Part 1:
Subjective method for the measurement of sound
attenuation
1 Scope
This document specifies a subjective method for measuring sound attenuation of hearing protectors
at the threshold of hearing. The method is a laboratory method designed to yield reproducible values
under controlled measurement conditions. The values reflect the attenuating characteristics of the
hearing protector only to the extent that users wear the device in the same manner as did the test
subjects.
For a more representative indication of field performance the methods of ISO/TS 4869-5 can be used.
This test method yields data which are collected at low sound pressure levels (close to the threshold
of hearing) but which are also representative of the attenuation values of hearing protectors at higher
sound pressure levels. An exception occurs in the case of amplitude-sensitive hearing protectors for
sound pressure levels above the point at which their level-dependent characteristics become effective.
At those sound pressure levels the method specified in this document is inapplicable, as it will usually
underestimate sound attenuation for these devices.
NOTE Due to masking from physiological noise in the occluded ear tests, sound attenuations below 500 Hz
can be overestimated by a few decibels.
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.
ISO 8253-2, Acoustics — Audiometric test methods — Part 2: Sound field audiometry with pure-tone and
narrow-band test signals
IEC 60263, Scales and sizes for plotting frequency characteristics and polar diagrams
IEC 61260-1, Electroacoustics — Octave-band and fractional-octave-band filters — Part 1: Specifications
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:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
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SIST EN ISO 4869-1:2019
ISO 4869-1:2018(E)
3.1
hearing protector
device worn by a person to prevent harmful effects from noise and other loud acoustic stimuli
Note 1 to entry: Hearing protectors can include electronic devices for communication, or devices designed to
play an active role in the reduction of the noise level between the hearing protector and the eardrum.
3.2
earmuff
hearing protector consisting of an ear-cup to be pressed against each pinna (supra-aural) or of an ear-
cup to be pressed against the head, around the pinna (circumaural)
Note 1 to entry: The ear-cups can be pressed against the head with a special headband or neck band or by means
of a device attached to a safety helmet or other equipment.
3.3
earplug
hearing protector worn within the external earcanal (aural) or in the concha against the entrance to
the external earcanal (semi-aural)
3.4
helmet
device which covers a substantial part of the head
3.5
hearing level (of a pure tone)
difference between the sound pressure level of this pure tone produced by the earphone in a specified
ear simulator or acoustic coupler and the appropriate reference equivalent threshold sound pressure
level at a specified frequency, for a specified type of earphone and for a specified manner of application
Note 1 to entry: Values of reference equivalent threshold sound pressure levels are specified in ISO 389-1.
3.6
hearing threshold level (of a given ear)
threshold of hearing expressed as hearing level at a specified frequency and for a specified type of
earphone
Note 1 to entry: For appropriate test conditions, see, for example, ISO 8253-1.
3.7
threshold of hearing
lowest sound pressure level at which, under specified conditions, a person gives a predetermined
percentage of correct detection responses on repeated trials
Note 1 to entry: For the purpose of ISO 4869-1, the threshold of hearing is measured with and without the hearing
protector. For appropriate test conditions, see ISO 8253-2.
3.8
sound attenuation
difference between the threshold of hearing with and without the hearing protector in place for a test
subject for a given test signal
Note 1 to entry: The sound attenuation is given in decibels.
3.9
pink noise
random noise signal with a spectral density that decreases by 3 dB per octave, giving constant energy
per octave
Note 1 to entry: The definition is often phrased as 'noise whose power spectral density is inversely proportional
to frequency'.
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SIST EN ISO 4869-1:2019
ISO 4869-1:2018(E)
[SOURCE: ISO 7240-24:2016, 3.1.11; modified: added Note 1 to entry]
3.10
reference point
fixed spatial position within the test chamber to which all objective measurements of the sound field
characteristics are referenced and which coincides with the midpoint of a line connecting the test
subject's earcanal openings when the test subject is seated for measurements
3.11
reverberation time
time required for the sound pressure level to decrease by 60 dB after the sound source has stopped
Note 1 to entry: See ISO 354 for information about measurement of reverberation time.
4 Measurement of the sound attenuation of hearing protectors
4.1 Test signals
The test signals shall consist of pink noise filtered through one-third-octave bands with centre
frequencies in accordance with IEC 61260-1. Tests shall be performed at the following centre
frequencies:
125 Hz, 250 Hz, 500 Hz, 1 000 Hz, 2 000 Hz, 4 000 Hz, 8 000 Hz.
Measurements at an additional centre frequency of 63 Hz are optional.
4.2 Test site
4.2.1 General
The sound field at the test site shall have sound incidence from many directions. Such a sound field is
adequately approximated when the requirements of 4.2.2, 4.2.3 and 4.2.4 are met. The measurements
of the sound field shall be conducted with the test subject and the subject's chair absent.
4.2.2 Sound pressure level and sound pressure level variation
a) The sound pressure level at all test frequencies measured with an omnidirectional microphone
at positions 15 cm from the reference point on the front-back, right-left and up-down axes shall
deviate by no more than ±2,5 dB from the sound pressure level at the reference point. In addition,
the difference between the right-left positions shall not exceed 3 dB. The orientation of the
microphone shall be kept the same at each position.
b) The directionality of the sound field shall be evaluated at the reference point for test signals with
centre frequencies greater than or equal to 500 Hz. The measurements shall be conducted with
a directional microphone with a typical free-field polar response at the one-third-octave test
signals of at least 10 dB front-to-side rejection for a cosine microphone, or at least 10 dB front-to-
back rejection for a cardioid microphone. The microphone shall be rotated at the reference point
through 360° in the horizontal plane. The variation of the observed sound pressure levels in each
test signal shall remain within the variation allowed in Table 1. The sound pressure levels can also
be obtained by measuring at fixed 15 degree increments as the microphone is rotated.
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ISO 4869-1:2018(E)
Table 1 — Allowable variation of sound-field sound pressure levels for corresponding
directional microphone free-field rejection
Microphone free-field rejection (FFR) Allowable field variation
dB dB
25 ≤ FFR 20
20 ≤ FFR < 25 15
15 ≤ FFR < 20 10
10 ≤ FFR < 15 5
FFR < 10 Microphone not suitable
NOTE The variation in microphone response as the microphone is rotated in a random incidence field is
related to the directional characteristics of the microphone and the degree of randomness of the field being
measured. Therefore, the allowable sound field response variations are related to the free-field directional
response characteristics of the microphone. The microphone characteristics can be obtained from the
microphone manufacturer or by measurement in a free field.
4.2.3 Reverberation time
The reverberation time in the test space, with the test subject and the test subject’s chair absent, shall
not exceed 1,6 s for each of the test signals.
4.2.4 Ambient noise level
The ambient noise level at the test site in the test room shall not exceed the values given in Table 2.
The ambient noise level shall be determined by measuring the sound pressure level with the test
subject absent.
When the lowest test signal centre frequency is 125 Hz, the ambient noise requirement shall be met
down to and including 63 Hz. When the lowest test signal centre frequency is 63 Hz, the ambient noise
requirement shall be met down to and including 31,5 Hz.
NOTE The ambient noise level includes the noise present in the room and the possible noise from the test
equipment while it is on and running, but in the absence of the test signals.
Table 2 — Maximum permissible ambient sound pressure level
Centre frequency One-third-octave-band
Hz sound pressure level
(reference = 20 μPa)
dB
31,5 57
40 43
50 31
63 25
80 21
100 18
125 14
160 11
200 9
250 6
315 4
NOTE The levels are set in relation to ISO 8253-1 for the purpose of testing down to
−10 dB hearing threshold level.
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ISO 4869-1:2018(E)
Table 2 (continued)
Centre frequency One-third-octave-band
Hz sound pressure level
(reference = 20 μPa)
dB
400 3
500 2
630 1
800 1
1 000 1
1 250 1
1 600 2
2 000 2
2 500 1
3 150 −1
4 000 −4
5 000 −2
6 300 3
8 000 10
10 000 20
NOTE The levels are set in relation to ISO 8253-1 for the purpose of testing down to
−10 dB hearing threshold level.
4.3 Test equipment
4.3.1 The test equipment shall be capable of producing a test signal at the test site from 112 Hz (or
56 Hz if the 63 Hz test signal is used) to 9 000 Hz.
NOTE 1 112 Hz is the lower limiting frequency of the 125 Hz one-third-octave band and 9 000 Hz is the upper
limiting frequency of the 8 000 Hz one-third-octave band.
The test equipment shall be able to generate test signal sound pressure levels at the reference point, for
any test signal, that vary from at least 10 dB above the subject’s occluded threshold of hearing to 10 dB
below the subject’s open threshold of hearing. An example is given in Annex C. The band levels shall be
measured using filters complying with IEC 61260-1. During the test, the sounds shall be reproduced
without audible distortion, buzzing, crackle, or rattle.
When the test equipment generates one-third-octave-band test signals at the maximum sound pressure
levels (Annex C) the levels of the other one-third-octave bands shall be at least 40 dB down from the
maximum level – at octave steps – from one octave below the test signal down to 31,5 Hz, and from one
octave above the test signal up to 16 kHz.
NOTE 2 Due to internal noise restrictions in the sound pressure level measurement equipment, low sound
pressure levels can be calculated on the basis of electrical measurements.
4.3.2 Attenuators shall have a range of at least 90 dB for each test signal. Attenuator steps shall be
2,5 dB or smaller.
4.3.3 The difference in output between any two attenuator settings, measured with a single one-third-
octave-band test signal (see 4.1), shall not differ from the indicated difference by more than 2 dB over
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ISO 4869-1:2018(E)
the total attenuator range and not more than 1 dB over any 80 dB range. Corrections for departure from
linearity shall be applied to the data when this requirement is not met.
Where possible this test shall be performed acoustically with a signal reproduced from all signal
channels simultaneously, so that the linearity can be measured under conditions approximating that
of the actual test and so as to include all parts of the measurement system that are potentially non-
linear. Appropriate time averaging is necessary. When the ratio of the acoustically measured sound
pressure level to the ambient noise is less than 20 dB, which can occur for the lowest level test signals,
the linearity of the signal voltage shall be measured at the terminals of the loudspeaker(s) using either
pure-tone or one-third-octave-band test signals.
4.3.4 To assure that the frequency response of the system remains constant over its dynamic range,
the frequency response of the system shall be measured in 10 dB steps from the maximum levels the
system can reproduce down to the noise floor set by the ambient noise level. For this test the one-third-
octave-band test signals (see 4.1) or a pink noise signal from 40 Hz to 10 kHz shall be used. The family of
frequency response curves thus generated shall show no departures from linearity of greater than 2 dB
for any of the one-third-octave test bands.
4.3.5 The test room shall be equipped with a viewing window or video system to allow clear
observation of the subject at all times during the test.
NOTE A head position reference device, such as a small hanging sphere to the nose or the forehead of the
subject, can be used to maintain the subject's head at the reference point. Care needs to be taken that the device
does not interfere with the threshold determination e.g. by transmitting vibrations to the head and that it is
small enough not to affect the uniformity of the sound field.
4.4 Test subjects
4.4.1 Sixteen test subjects shall be used for each test.
4.4.2 Test subjects to be used in the tests shall have a pure-tone hearing threshold level by earphone
listening in either ear of no more than 15 dB for frequencies of 2 000 Hz and below, and of no more than
25 dB for frequencies above 2 000 Hz.
When the ambient noise in the test room is at the maximum levels listed in Table 2, test subjects with
hearing threshold levels lower than −10 dB shall be rejected.
4.4.3 Test subjects shall be selected without regard to sizes and shapes of heads and ears except that
those with obvious abnormalities affecting the fitting of hearing protectors shall be excluded.
4.4.4 Test subjects used for the test shall have demonstrated the ability to provide three consecutive
complete threshold determinations for the test signals given in 4.1, with differences between the
thresholds of hearing at corresponding centre frequencies not exceeding 6 dB. Untrained test subjects
should first be given practice sessions.
4.5 General test procedure and instruction of the test subject
4.5.1 The attenuation measurement is described in 4.6.
A minimum of four samples of an earmuff hearing protector under test shall be used. The samples shall
be evenly distributed among the test subjects. Test subjects shall use the same pro
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