EN ISO 4869-2:1995
(Main)Acoustics - Hearing protectors - Part 2: Estimation of effective A-weighted sound pressure levels when hearing protectors are worn (ISO 4869-2:1994)
Acoustics - Hearing protectors - Part 2: Estimation of effective A-weighted sound pressure levels when hearing protectors are worn (ISO 4869-2:1994)
Describes three methods (the octave-band, HML and SNR methods) for estimating the A-weighted sound pressure levels effective when hearing protectors are worn. The methods are applicable to either the sound pressure level or the equivalent continuous sound pressure level of the noise. Although primarily intended for steady noise exposures, the methods are also applicable to noises containing impulsive components. They are not suitable for use with peak sound pressure level measurements.
Akustik - Gehörschützer - Teil 2: Abschätzung der beim Tragen von Gehörnschützern wirksamen A-bewerteten Schalldruckpegel (ISO 4869-2:1994)
Dieser Teil von ISO 4869 legt drei Verfahren zur Abschätzung des beim Tragen von Gehörschützern wirksamen A-bewerteten Schalldruckpegels fest (das Oktavpegel-, das HML- und das SNR-Verfahren). Die Verfahren sind entweder auf den Schalldruckpegel des Geräusches oder dessen äquivalenten Dauerschalldruck-pegel anwendbar. Obwohl sie primär für den Fall der Einwirkung stationär Geräusche bestimmt sind, sind sie auch auf impulshaltige Geräusche anwendbar. Diese Verfahren sind nicht für Spitzenschalldruckpegelmessungen geeignet.
Acoustique - Protecteurs individuels contre le bruit - Partie 2: Estimation des niveaux de pression acoustique pondérés A en cas d'utilisation de protecteurs individuels contre le bruit (ISO 4869-2:1994)
La présente partie de l'ISO 4869 décrit trois méthodes (la méthode par bande d'octave, la méthode HML et la méthode SNR) pour estimer les niveaux de pression acoustique effectifs pondérés A en cas d'utilisation de protecteurs individuels contre le bruit. Ces méthodes s'appliquent soit au niveau de pression acoustique, soit au niveau de pression acoustique continu équivalent du bruit. Bien que prévues essentiellement pour des expositions à un bruit continu, ces méthodes s'appliquent également à des bruits comportant des composantes impulsives. Ces méthodes ne conviennent pas aux mesurages du niveau de pression acoustique de crête. Les valeurs de bande d'octave, H, M, L ou SNR conviennent pour établir des critères d'affaiblissement acoustique de manière à sélectionner ou à comparer les protecteurs individuels contre le bruit et/ou à établir des exigences d'affaiblissement acoustique minimales acceptables.
Akustika – Oprema za varovanje sluha - 2. del: Ocena efektivne A-vrednotene ravni zvočnega tlaka pri nošenju osebne varovalne opreme pred hrupom (ISO 4869-2:1994)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-1999
$NXVWLND±2SUHPD]DYDURYDQMHVOXKDGHO 2FHQDHIHNWLYQH$YUHGQRWHQHUDYQL
]YRþQHJDWODNDSULQRãHQMXRVHEQHYDURYDOQHRSUHPHSUHGKUXSRP ,62
Acoustics - Hearing protectors - Part 2: Estimation of effective A-weighted sound
pressure levels when hearing protectors are worn (ISO 4869-2:1994)
Akustik - Gehörschützer - Teil 2: Abschätzung der beim Tragen von Gehörnschützern
wirksamen A-bewerteten Schalldruckpegel (ISO 4869-2:1994)
Acoustique - Protecteurs individuels contre le bruit - Partie 2: Estimation des niveaux de
pression acoustique pondérés A en cas d'utilisation de protecteurs individuels contre le
bruit (ISO 4869-2:1994)
Ta slovenski standard je istoveten z: EN ISO 4869-2:1995
ICS:
13.340.20 Varovalna oprema za glavo Head protective equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL
IS0
STANDARD
4869-2
First edition
1994-09-O 1
Acoustics - Hearing protectors -
Part 2:
Estimation of effective A-weighted sound
pressure levels when hearing protectors are
worn
Acoustique
- Protecteurs individuels con tre le bruit -
Par-tie 2: Estimation des niveaux de pression acoustique pond&& A en
cas d ’utilisa tion de pro tecteurs individuels con tre le bruit
Reference number
IS0 4869-Z: 1994(E)
IS0 4869=2:1994(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, governmental
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 International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 4869-2 was prepared by Technical Committee
ISOnC 43, Acoustics, Subcomm ttee SC 1, Noise.
IS0 4869 consists of the fol owing parts, under the general title
Acoustics - Hearing pro tee tors:
- Part 7: Subjective method for the measurement of sound attenu-
a tion
- Part 2: Estimation of effective A-weighted sound pressure levels
when hearing protectors are worn
- Part 3: Simplified method for the measurement of insertion loss of
ear-muff type protectors for quality inspection purposes
[Technical Report]
sound attenuation of
- Part 4: Methods for the measurement of
litude-sensitive hearing protectors
amp
Annexes A, B, C, D and E of this part of IS0 4869 are for information only.
0 IS0 1994
All rights reserved. Unless otherwise specified, 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 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
0 IS0
IS0 4869-2: 1994(E)
Introduction
Ideally, the A-weighted sound pressure level effective when a hearing
protector is worn should be estimated on the basis of both the octave-
band sound attenuation data of the hearing protector (measured in ac-
cordance with IS0 4869-l) and the octave-band sound pressure levels of
the noise. It is recognized, however, that in many situations information
on the octave-band sound pressure levels of the noise might not be
available. Therefore, for many practical purposes, there is a need for sim-
pler methods to determine the effective A-weighted sound pressure levels
which are only based on the A- and C-weighted sound pressure levels of
the noise. This part of IS0 4869 addresses both of these situations by
specifying an octave-band calculation method as well as two alternative
simplified procedures, the HML method and the SNR method.
The octave-band method is a straightforward calculation method involving
the workplace octave-band sound pressure levels and the octave-band
sound attenuation data for the hearing protector which is being assessed.
Although it can be thought of as an “exact” reference method, it has its
own inherent inaccuracies, since it is based upon mean sound attenuation
values and standard deviations and not the specific sound attenuation
values for the individual person in question.
The HML method specifies three attenuation values, H, M and L, deter-
mined from the octave-band sound attenuation data of a hearing protector.
These values, when combined with the C- and A-weighted sound pressure
levels of the noise, are used to calculate the effective A-weighted sound
pressure level when the hearing protector is worn.
The SNR method specifies a single attenuation value, the single number
rating reduction, determined from the octave-band sound attenuation data
of a hearing protector. This value is subtracted from the C-weighted sound
pressure level of the noise to calculate the effective A-weighted sound
pressure level when the hearing protector is worn.
Due to the large spread of the sound attenuation provided by hearing
. protectors when worn by individual persons, all three methods are nearly
equivalent in their accuracy in the majority of noise situations. Even the
simplest method, the SNR method, will provide a reasonably accurate
estimate of the effective A-weighted sound pressure level to aid in the
selection and specification of hearing protectors. In special situations, for
example especially high- or low-frequency noises, it may, however, be
advantageous to use either the HML or the octave-band method.
Depending on the choice of a certain parameter in the calculation process,
various protection performances can be obtained. It should be noted that
the protection performance values for all three methods are only valid
when:
- the hearing protectors are worn correctly and in the same manner as
they were worn by subjects when carrying out the IS0 4869-l test;
. . .
III
0 IS0
IS0 4869-2: 1994(E)
- the hearing protectors are properly maintained;
- the anatomical characteristics of the subjects involved in the
IS0 4869-l test are a reasonable match for the population of actual
wea re rs.
Thus, the principal source of potential inaccuracy in use of the three
methods described in this part of IS0 4869 is the basic IS0 4869-l input
data. If the input data do not accurately describe the degree of protection
achieved by the target population, then no calculation method will provide
sufficient accuracy.
NOTES
1 Differences of 3 dB or less in the determination of the effective sound pressure
level for comparable hearing protectors are insignificant for the purposes of dis-
tinguishing between the hearing protectors.
2 Caution should be exercised to avoid the selection of hearing protectors which
provide unnecessarily high attenuation. Such devices might cause communication
difficulties or be less comfortable than ones with lower sound attenuation and
therefore they might be worn for less of the time.
IS0 4869=2:1994(E)
INTERNATIONAL STANDARD 0 IS0
- Hearing protectors -
Acoustics
Part 2:
Estimation of effective A-weighted sound pressure levels
when hearing protectors are worn
IEC 651:1979, Sound level meters.
1 Scope
This part of IS0 4869 describes three methods (the
3 Definitions
octave-band, HML and SNR methods) of estimating
the A-weighted sound pressure levels effective when
For the purposes of this part of IS0 4869, the defi-
hearing protectors are worn. The methods are appli- nitions given in IS0 4869-l and the following defi-
cable to either the sound pressure level or the equiv- nitions apply.
alent continuous sound pressure level of the noise.
3.1 protection performance: The percentage of
Although primarily intended for steady noise ex-
posures, the methods are also applicable to noises situations for which the A-weighted sound pressure
containing impulsive components. These methods are level effective when the hearing protector is worn is
not suitable for use with peak sound pressure level equal to or less than the predicted value.
measurements.
The value is designated by adding a subscript to the
attenuation values according to the different methods,
The octave-band, H, M, L or SNR values are suitable
for establishing sound attenuation criteria for selecting e.g. H80, Me01 L80, SNhjf)-
or comparing hearing protectors, and/or setting mini-
NOTES
mum acceptable sound attenuation requirements.
3 The value of protection performance is often chosen to
be 84 % [corresponding to the constant a = 1 (see
clause 5)]. In this case, the subscripts to the attenuation
2 Normative references
values may be omitted.
The following standards contain provisions which,
4 A situation is a combination of a particular individual
through reference in this text, constitute provisions
wearing a given hearing protector in a specific noise en-
of this part of IS0 4869. At the time of publication, the vironment.
editions indicated were valid. All standards are subject
to revision, and parties to agreements based on this 3.2 effective A-weighted sound pressure level,
part of IS0 4869 are encouraged to investigate the I,‘,: For a specified protection performance, X, and a
possibility of applying the most recent editions of the specific noise situation, the A-weighted sound press-
ure level effective when a given hearing protector is
standards indicated below. Members of IEC and IS0
worn, calculated in accordance with any of the three
maintain registers of currently valid International
Standards. methods specified in this part of IS0 4869.
IS0 4869-l :I 990, Acoustics - Hearing protectors - 3.3 predicted noise Ilevel reduction, PNR,: For a
Part I: Subjective method for the measurement of specified protection performance, X, and a specific
sound attenuation. noise situation, the difference between the A-
l
0 IS0
IS0 4869-2: 1994(E)
weighted sound pressure level of the noise, LA, and
APVf, = 9 - asf . . .
(1)
the effective A-weighted sound pressure level, L ’,,
when a given hearing protector is worn.
where
3.4 high-frequency attenuation value, H,: For a
subscriptf represents the centre frequency of
specified protection performance, X, and a given the octave band;
hearing protector, a value representing the predicted
subscript x represents the selected protection
noise level reduction, PNR,, for noises with
performance;
(Lc -LA) = - 2 dB.
is the mean sound attenuation de-
!f
3.5 medium-frequency attenuation value, M,: For
termined in accordance with
a specified protection performance, X, and a given
IS0 4869-l ;
hearing protector, a value representing the predicted
noise level reduction, PNR,, for noises with
is the standard deviation deter-
sf
(Lc -LA) = + 2 dB.
mined in accordance with
IS0 4869-l ;
3.6 low-frequency attenuation value, LX: For a
specified protection performance, X, and a given
a is a constant, having the values
hearing protector, a value representing the predicted
given in table 1.
level reduction, PNR,, for noises with
noise
&-LA) = + 10 dB. NOTE 6 If any values are not available at 63 Hz, then the
values of ngc and sf for 125 Hz should be used.
3.7 single number rating, SNR,: For a specified
protection performance, X, and a given hearing pro-
Table 1 - Values of a for various protection
tector, the value which is subtracted from the meas-
performances x
ured C-weighted sound pressure level, L,, in order to
estimate the effective A-weighted sound pressure
Protection performance
level, L ’,.
Value of a
x, %
3.8 pink noise: Noise whose power spectral density
75 0,67
is inversely proportional to frequency.
80 0,84
NOTE 5 A consequence of this property of pink noise is
84 1 ,oo
that its unweighted octave-band sound pressure levels are
85 I,04
the same for all octave bands.
1,28
I,64
4 Measurement of sound attenuation of
hearing protectors
An example of the calculation of the assumed pro-
The one-third-octave band attenuation values of the
tection values, APVfi, is given in annex A.
hearing protector to be used in the calculation meth-
ods specified in this part of IS0 4869 shall be meas-
ured in accordance with IS0 4869-l.
6 Octave-band method
5 Calculation of the assumed protection
This method requires octave-band sound pressure
value, APVf,, of a hearing protector for a
levels of the noise and assumed protection values,
selected protection performance
APV,. Since the method is noise specific, the calcu-
lation shall be made for each noise situation.
The calculation begins with the selection of the de-
sired protection performance, X, and the associated
The A-weighted sound pressure level effective when
constant a (see table 1).
the hearing protector is worn, L ’,, is calculated using
the following equation:
The assumed protection value, APVf,, of the hearing
protector is calculated for each octave band, in the
range 63 Hz to 8 000 Hz, using the following (2)
equation:
0 IS0
IS0 4869-2: 1994(E)
where values (see table2) and the assumed protection val-
ues, APVfX, of the hearing protector. The values are
subscripts f(k) represent the octave-band mid-
independent of the actual noise situation to which
frequency;
they are applied, and are calculated using the follow-
ing equations:
f(1) = 63 Hz; f(2) = 125 Hz; f(3) = 250 Hz . . .
4 4
f(8) = 8 000 Hz;
H, = 0,25T,PNR,i - 0,48T,diPNR, . . . (3)
i=l i=l
is the sound pressure level of the noise in
Lf (k)
8 8
the octave band;
M, = 0,257, PNR,i - 0,16F,diPNR, l . . (4)
is the frequency weighting A in accord- i=5 i=5
Afck,
ance with IEC 651 at the octave-band
8 8
mid-frequencies (see table B.1).
Lx = 0,257,PNRxi + 0,23F,diPNR,i l . .
(5)
i=5 i=5
NOTE 7 If 63 Hz octave-band data for the noise are not
available, then the summation in equation (2) begins at
where
125 Hz.
PNR,i
= 1 00 d B 1 1 0 Ig T,l O ”l’ &W - APvfW) d B
The resulting L ’, value shall be rounded to the near-
est integer.
k=l
. . .
(6)
An exampl
...
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