Bsi bs en 24869 1 1993 (1999) iso 4869 1 1990

00374187 PDF BRITISH STANDARD BS EN 24869 1 1993 ISO 4869 1 1990 Incorporating Amendment No 1 Sound attenuation of hearing protectors — Part 1 Subjective method of measurement The European Standard EN[.]

BRITISH STANDARD BS EN

24869-1:1993 ISO 4869-1: 1990

Incorporating Amendment No 1

Sound attenuation of

hearing protectors —

Part 1: Subjective method of

measurement

The European Standard EN 24869-1:1992 has the status of a

British Standard

UDC 614.892:620.1:534.61:534.833.5

BS EN 24869-1:1993

This British Standard, having

been prepared under the

direction of the Environment

and Pollution Standards Policy

Committee, was published

under the authority of the

Standards Board and comes

into effect on

28 June 1991

© BSI 08-1999

First published July 1974

Second edition September 1983

Third edition June 1991

The following BSI references

relate to the work on this

standard:

Committee reference EPC/1

Draft announced in BSI News

July 1989

ISBN 0 580 19628 3

Committees responsible for this British Standard

The preparation of this British Standard was entrusted by the Environment and Pollution Standards Policy Committee (EPC/-) to Technical Committee EPC/1, upon which the following bodies were represented:

Association of Consulting Engineers British Broadcasting Corporation British Occupational Hygiene Society British Telecommunications plc Department of Health

Department of the Environment (Building Research Establishment) Department of Trade and Industry (Air Division)

Department of Trade and Industry (National Physical Laboratory) Engineering Equipment and Materials Users’ Association Health and Safety Executive

Incorporated Association of Architects and Surveyors Institute of Acoustics

Institute of Occupational Hygienists Institute of Physics

Institute of Sound and Vibration Research Institution of Civil Engineers

Institution of Electrical Engineers Royal Institute of British Architects Society of Environmental Engineers Transmission and Distribution Association (BEAMA Ltd.)

The following bodies were also represented in the drafting of the standard, through subcommittees and panels:

Electricity Supply Industry in UK Industrial Safety (Protective Equipment) Manufacturers’ Association Institution of Mechancial Engineers

Ministry of Defence Society of Hearing Aid Audiologists Ltd.

University of Salford

Amendments issued since publication

Amd No Date Comments

7552 February 1993 Indicated by a sideline in the margin

BS EN 24869-1:1993

Contents

Page Committees responsible Inside front cover

4 Measurement of the sound attenuation of hearing protectors 4 Annex A (informative) Uncertainty of sound attenuation measurements 8 Annex B (informative) Bibliography 8 Table 1 — Allowable field variation for different microphones 5 Table 2 — Maximum permissible background sound pressure level 5 Table 3 — Minimum and maximum sound pressure levels for test signals 5 Table A.1 — Repeatability and reproducibility of sound attenuation

measurements on ear-muffs at a probability level of 95 %

Table A.2 — Repeatability and reproducibility of sound attenuation measurements on ear-plugs at a probability level of 95 %

Publication(s) referred to Inside back cover

BS EN 24869-1:1993

National foreword

This Part of BS 5108 has been prepared under the direction of the Environment and Pollution Standards Policy Committee It is identical with ISO 4869-1:1990

“Acoustics — Hearing protectors — Part 1: Subjective method for the measurement

of sound attenuation”, published by the International Organization for

Standardization (ISO) ISO 4869-1 was prepared by Subcommittee 1, Noise, of ISO Technical Committee 43, Acoustics, with the active participation and approval of the UK It constitutes a minor revision of ISO 4869:1981

In 1992 the European Committee for Standardization (CEN) accepted ISO 4869-1:1990 as European Standard EN 24869-1:1992 As a consequence of implementing the European Standard this British Standard is renumbered as

BS EN 24869-1 and any reference to BS 5108-1:1991 should be read as a reference to BS EN 24869-1

This Part of BS 5108 is a revision of BS 5108:1983, which is withdrawn

Further revised Parts of BS 5108 are in preparation A second Part will be based

on ISO 4869-2 “Estimated noise reduction of hearing protectors” and a third Part

is envisaged, based on a future revision of ISO/TR 4869-3:1989 “Simplified

method for the measurement of insertion loss of ear-muff type protectors for quality inspection purposes” which was implemented, dual-numbered as DD 192:1990.

Hearing protectors are commonly used to reduce the noise to which the ear is exposed Hearing protectors are manufactured as ear-plugs, ear-muffs or helmets A standardized method of sound attenuation measurement allows performance data obtained in different locations under similar conditions to be compared The data may be used for rank ordering and selection of different models and the evaluation of design and construction features that affect performance

Cross-references

International Standard Corresponding British Standard

ISO 354:1985 BS 3638:1987 Method for measurement of sound

absorption in a reverberation room

(Identical) ISO 389:1985 BS 2497 Standard reference zero for the calibration of

pure tone air conduction audiometers

Part 5:1988 Specification for a standard reference zero

using an acoustic coupler complying with BS 4688

(Identical) ISO 5725:1986 BS 5497 Precision of test methods

Part 1:1987 Guide for the determination of repeatibility

and reproducibility for a standard test method by inter-laboratory tests

(Identical) ISO 6189:1983 BS 6655:1986 Specification for pure tone air conduction

threshold audiometry for hearing conservation purposes

(Identical) IEC 225:1966 BS 2475:1964 Specification for octave and one-third

octave band-pass filters

(Technically equivalent) IEC 263:1982 BS 6397:1983 Specification for scales and sizes for

plotting frequency characteristics and polar diagrams

(Identical)

BS EN 24869-1:1993

The Technical Committee has reviewed the provisions of ISO 8253-2, to which

reference is made in clause 2 and 4.5.5 and in a note to 3.7, and of the draft of IEC 645-1, to which reference is made in clause 2 and 4.3.4, and has decided that

they are acceptable for use in conjunction with this standard ISO 8253-1, to

which reference is made in a note to 3.6 and in the informative bibliography, is

given for information only and does not affect the use of this Part of BS 5108

A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application

Compliance with a British Standard does not of itself confer immunity from legal obligations.

International Standard Corresponding British Standard

IEC 651:1979 BS 5969:1981 Specification for sound level meters

(Identical) IEC 804:1985 BS 6698:1986 Specification for integrating-averaging

sound level meters

(Identical)

Summary of pages

This document comprises a front cover, an inside front cover, pages i to iv, the EN title page, pages 2 to 8, an inside back cover and a back cover

This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover

iv blank

EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 24869-1 October 1992

UDC 614.892:620.1:534.61:534.833.5

Descriptors: Acoustics, ear protectors, acoustic measurement, noise reduction

English version

Acoustics — Hearing protectors — Subjective method for

the measurement of sound attenuation

(ISO 4869-1:1990)

Acoustique — Protecteurs individuels contre le

bruit — Méthode subjective de mesurage de

l’affaiblissement acoustique

(ISO 4869-1:1990)

Akustik — Gehörschützer — Subjektive Methode zur Messung der Schalldämmung (ISO 4869-1:1990)

This European Standard was approved by CEN on 1992-10-16 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 Central Secretariat 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

Central Secretariat has the same status as the official versions

CEN members are the national standards bodies of Austria, Belgium,

Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,

Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and

United Kingdom

CEN

European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung

Central Secretariat: rue de Stassart 36, B-1050 Brussels

© 1992 Copyright reserved to CEN members

Ref No EN 24869-1:1992 E

EN 24869-1:1992

© BSI 08-1999

2

Foreword

This European Standard is the endorsement of

ISO 4869-1 Endorsement of ISO 4869-1 was

recommended by Technical Committee CEN/TC 211

“Acoustics” under whose competence this European

Standard will henceforth fall

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

April 1993, and conflicting national standards shall

be withdrawn at the latest by April 1993

The Standard was approved and in accordance with

the CEN/CENELEC Internal Regulations the

following countries are bound to implement this

European Standard: Austria, Belgium, Denmark,

Finland, France, Germany, Greece, Iceland,

Ireland, Italy, Luxembourg, Netherlands, Norway,

Portugal, Spain, Sweden, Switzerland,

United Kingdom

EN 24869-1:1992

1 Scope

This International Standard specifies a subjective

method for measuring sound attenuation of hearing

protectors at the threshold of hearing The method

and procedures are designed to yield values close to

the maximum attenuation which are not normally

attained under field conditions This approach has

been adopted because the attenuation values can

then be consistently reproduced 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

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 International Standard is inapplicable; it will

usually underestimate sound attenuation for these

devices

NOTE 1 At low frequencies (below 500 Hz) the sound

attenuation may be overestimated by a few decibels as a result of

masking the occluded ear thresholds caused by physiological

noise during the occluded ear tests.

2 Normative references

The following standards contain provisions which,

through reference in this text, constitute provisions

of this part of ISO 4869 At the time of publication,

the editions indicated were valid All standards are

subject to revision, and parties to agreements based

on this part of ISO 4869 are encouraged to

investigate the possibility of applying the most

recent editions of the standards indicated below

Members of IEC and ISO maintain registers of

currently valid International Standards

ISO 354:1985, Acoustics — Measurement of sound

absorption in a reverberation room

ISO 8253-2:—, Acoustics — Audiometric test

methods — Part 2: Sound field audiometry with

pure tone and narrow-band test signals1)

IEC 225:1966, Octave, half-octave and third-octave

band filters intended for the analysis of sounds and

vibrations

IEC 263:1982, Scales and sizes for plotting

frequency characteristics and polar diagrams

IEC 645-1:—, Audiometers — Part 1: Pure tone

audiometers2)

IEC 651:1979, Sound level meters

IEC 804:1985, Integrating-averaging sound level

meters

3 Definitions

For the purposes of this part of ISO 4869, the following definitions apply

3.1 hearing protector

a device worn by a person to prevent unwanted auditory effects from acoustic stimuli

NOTE 2 Hearing protectors may 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 ear-drum.

3.2 ear-muff

a hearing protector consisting of an ear-cup to be pressed against each pinna or of a circumaural ear-cup to be pressed against the head around the pinna 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 ear-plug

a hearing protector worn within the external ear canal (aural) or in the concha against the entrance

to the external ear canal (semi-aural)

3.4 helmet

a device which covers a substantial part of the head

3.5 hearing level (of a pure tone)

at a specified frequency, for a specified type of earphone and for a specified manner of application, the sound pressure level of this pure tone produced

by the earphone in a specified acoustic coupler or artificial ear minus the appropriate reference equivalent threshold sound pressure level

NOTE 3 Values of reference equivalent threshold sound pressure levels are specified in ISO 389.

3.6 hearing threshold level (of a given ear)

at a specified frequency and for a specified type of earphone, the threshold of hearing expressed as hearing level

NOTE 4 For appropriate test conditions see, for example, ISO 6189 and ISO 8253-1.

1) To be published.

2) To be published (Revision of IEC 645:1979.)

EN 24869-1:1992

3.7

threshold of hearing

the lowest sound pressure level at which, under

specified conditions, a person gives a predetermined

percentage of correct detection responses on

repeated trials

NOTE 5 For the purpose of this International Standard, the

threshold of hearing is measured with and without the hearing

protector For appropriate test conditions, see ISO 8253-2.

3.8

sound attenuation

for a given test signal, the difference, in decibels,

between the threshold of hearing with and without

the hearing protector in place for a test subject

3.9

pink noise

noise the sound pressure spectral density of which is

inversely proportional to frequency

3.10

reference point

the midpoint of a line connecting the test subject’s

ear canal openings

3.11

reverberation time

the time required for the sound pressure level to

decrease by 60 dB after the sound source has

stopped (see ISO 354)

3.12

repeatability

the value below which the absolute difference

between two single test results obtained with the

same method on identical test material, under the

same conditions (same operator, same apparatus,

same laboratory, and a shod interval of time), may

be expected to lie with a specified probability; in the

absence of other indications, the probability is 95 %

3.13

reproducibility

the value below which the absolute difference

between two single test results obtained with the

same method on identical test material, under

different conditions (different operators, different

apparatus, different laboratories and/or different

time), may be expected to lie with a specified

probability; in the absence of other indications, the

probability is 95 %

4 Measurement of the sound attenuation of hearing protectors

4.1 Test signals

The test signals shall consist of a signal from pink noise filtered through one-third octave bands with centre frequencies in accordance with IEC 225 Tests shall be performed at the following centre frequencies:

4.2 Test site 4.2.1 Diffuse sound field conditions are required and are adequately approximated when the following requirements are met:

a) With the test subject and the subject’s chair absent, the sound pressure level 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 for any of the test signals Further, the difference between the extreme right-left positions shall not exceed 3 dB The orientation of the microphone shall be kept the same at each position

b) At frequencies of 500 Hz and above, the sound pressure level at the reference point shall be within 5 dB for the two directions of

measurement that give maximum and minimum readings of the incident sound energy when measured with a directional microphone with a front-to-random sensitivity index of 5 dB For other directional microphones the relationship between front-to-random sensitivity index and the allowable field variation is given in Table 1

63 Hz (optional)

125 Hz

250 Hz

500 Hz

1 000 Hz

2 000 Hz

4 000 Hz

8 000 Hz