SIST EN IEC 61252:2026

SLOVENSKI STANDARD
01-marec-2026
Nadomešča:
SIST EN 61252:2000
SIST EN 61252:2000/A1:2002
SIST EN 61252:2000/A2:2017
Elektroakustika - Merilniki osebne izpostavljenosti zvoku (IEC 61252:2025)
Electroacoustics - Personal sound exposure meters (IEC 61252:2025)
Elektroakustik - Anforderungen an Personenschallexposimeter (IEC 61252:2025)
électroacoustique - Exposimètres acoustiques individuels (IEC 61252:2025)
Ta slovenski standard je istoveten z: EN IEC 61252:2025
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
17.140.50 Elektroakustika Electroacoustics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61252

NORME EUROPÉENNE
EUROPÄISCHE NORM November 2025
ICS 13.140; 17.140.50 Supersedes EN 61252:1995; EN 61252:1995/A1:2001;
EN 61252:1995/A2:2017
English Version
Electroacoustics - Personal sound exposure meters
(IEC 61252:2025)
Électroacoustique - Exposimètres acoustiques individuels Elektroakustik - Anforderungen an
(IEC 61252:2025) Personenschallexposimeter
(IEC 61252:2025)
This European Standard was approved by CENELEC on 2025-11-21. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61252:2025 E
European foreword
The text of document 29/1206/FDIS, future edition 2 of IEC 61252, prepared by TC 29
"Electroacoustics" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2026-11-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-11-30
document have to be withdrawn
This document supersedes EN 61252:1995 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61252:2025 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 61094-1 NOTE Approved as EN 61094-1
IEC 61094-4 NOTE Approved as EN 61094-4
IEC 61252:1993 NOTE Approved as EN 61252:1995 (not modified)
ISO 9612 NOTE Approved as EN ISO 9612
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60942 - Electroacoustics - Sound calibrators EN IEC 60942 -
IEC 61000-4-3 2020 Electromagnetic compatibility (EMC) - Part EN IEC 61000-4-3 2020
4-3 : Testing and measurement techniques
- Radiated, radio-frequency,
electromagnetic field immunity test
IEC 61094-6 - Measurement microphones - Part 6: EN 61094-6 -
Electrostatic actuators for determination of
frequency response
IEC 61183 - Electroacoustics - Random-incidence and EN 61183 -
diffuse-field calibration of sound level
meters
IEC 61672 - Electroacoustics-Sound level meters - -
IEC 61672-1 2013 Electroacoustics - Sound level meters - EN 61672-1 2013
Part 1: Specifications
IEC 61672-2 2013 Electroacoustics - Sound level meters - EN 61672-2 2013
Part 2: Pattern evaluation tests
IEC 61672-3 2013 Electroacoustics - Sound level meters - EN 61672-3 2013
Part 3: Periodic tests
IEC 62585 2012 Electroacoustics - Methods to determine EN 62585 2012
corrections to obtain the free-field
response of a sound level meter
ISO/IEC Guide 98-3 - Uncertainty of measurement - Part 3: - -
Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO/IEC Guide 98-4 - Uncertainty of measurement -- Part 4: Role - -
of measurement uncertainty in conformity
assessment
ISO/IEC Guide 99 - International vocabulary of metrology_- - -
Basic and general concepts and
associated terms (VIM)
IEC 61252 ®
Edition 2.0 2025-10
INTERNATIONAL
STANDARD
Electroacoustics - Personal sound exposure meters

ICS 13.140; 17.140.50 ISBN 978-2-8327-0674-9

IEC 61252:2025-10(en)
IEC 61252:2025 © IEC 2025
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Performance specifications . 12
4.1 General performance requirements. 12
4.1.1 Components . 12
4.1.2 Display device . 12
4.1.3 Configuration . 13
4.1.4 Design features . 13
4.1.5 Adjustment at the calibration check frequency. 15
4.1.6 Determination of conformance . 16
4.1.7 Reference environmental conditions . 16
4.1.8 Classification for radio-frequency tests . 17
4.2 Marking . 17
4.3 Static pressure . 17
4.4 Temperature . 17
4.5 Relative humidity . 18
4.6 Electrostatic discharge . 18
4.7 AC-power-frequency and radio-frequency fields . 18
4.8 Radio-frequency emissions and disturbances to a public power supply. 18
4.9 Directional response . 18
4.10 Frequency weightings . 19
4.11 Corrections to indicated levels . 19
4.11.1 General. 19
4.11.2 Windscreens . 20
4.11.3 Corrections for use during periodic testing . 20
4.12 Linearity of response to steady signals . 21
4.13 Under-range indication . 21
4.14 Time-weightings F and S . 21
4.15 Response to short duration signals for indications of time-averaged sound
levels, sound exposure levels, and time-weighted sound levels . 21
4.16 Response to short duration signals for indications of time-averaged non-
equal-energy sound levels . 21
4.17 Overload indication . 22
4.18 C-weighted peak sound level . 23
4.18.1 Deviation from reference differences . 23
4.18.2 Repeatability . 23
4.19 Stability during continuous operation . 23
4.20 High-level stability . 23
4.21 Reset facility . 23
4.22 Analogue or digital output . 23
4.23 Timing facilities . 23
4.24 Crosstalk . 24
4.25 Power supply . 24
4.26 Pause and resumption of time averaging and time integration . 24
IEC 61252:2025 © IEC 2025
4.27 Instruction manual . 24
4.27.1 General. 24
4.27.2 Specifications . 24
4.27.3 Information for operation. 26
4.27.4 Information for use with auxiliary devices . 27
4.27.5 Information for testing . 28
5 Pattern-evaluation tests. 28
5.1 General requirements. 28
5.1.1 Submission for testing . 28
5.1.2 Display device . 29
5.1.3 Configuration . 29
5.1.4 Design features . 30
5.1.5 Adjustment at the calibration check frequency. 30
5.1.6 Determination of conformance . 31
5.1.7 Environmental conditions . 31
5.1.8 Laboratory equipment . 32
5.2 Marking and information in the instruction manual . 32
5.3 Static pressure . 32
5.4 Temperature . 32
5.5 Relative humidity . 32
5.6 Electrostatic discharge . 32
5.7 Influence of AC-power-frequency and radio-frequency fields . 32
5.8 Radio-frequency emissions and public power supply disturbances . 32
5.9 Directional response . 33
5.10 Frequency weightings . 33
5.10.1 Acoustical signal tests of frequency weightings . 33
5.10.2 Electrical signal tests of frequency weightings . 33
5.11 Corrections to indicated levels . 33
5.12 Linearity of response to steady signals . 33
5.13 Under-range indication . 33
5.14 Decay time constants for time weightings F and S . 33
5.15 Response to short-duration signals for indications of time-averaged sound
levels, sound exposure levels, and time-weighted sound levels . 33
5.16 Response to short-duration signals for indications of time-averaged non-
equal-energy sound levels . 34
5.17 Overload indication . 34
5.18 C-weighted peak sound level . 34
5.18.1 Deviation from reference differences . 34
5.18.2 Repeatability . 34
5.19 Stability during continuous operation . 35
5.20 High-level stability . 35
5.21 Reset facility . 35
5.22 Outputs . 35
5.23 Timing facilities . 35
5.24 Crosstalk in multi-channel personal sound exposure meters . 35
5.25 Power supply . 35
5.26 Pause and resumption of time averaging and time integration . 36
5.27 Pattern evaluation report . 36
6 Periodic tests . 36
IEC 61252:2025 © IEC 2025
6.1 General requirements. 36
6.1.1 Submission for testing . 36
6.1.2 Preliminary inspection . 37
6.1.3 Configuration . 38
6.1.4 Design features . 38
6.1.5 Adjustment at the calibration check frequency. 38
6.1.6 Determination of conformance . 38
6.1.7 Environmental conditions . 39
6.1.8 Laboratory equipment . 40
6.1.9 Power supply . 40
6.2 Marking . 40
6.3 Frequency weightings . 40
6.3.1 Acoustical signal tests of a frequency weighting . 40
6.3.2 Electrical signal tests of frequency weightings . 40
6.4 Frequency and time weightings at 1 kHz . 41
6.5 Linearity of response to steady signals . 41
6.6 Response to short-duration signals for indications of time-averaged sound
levels . 41
6.7 Response to short-duration signals for indications of time-averaged non-
equal-energy sound levels . 41
6.8 Overload indication . 41
6.9 C-weighted peak sound level . 41
6.9.1 Deviation from reference differences . 41
6.9.2 Repeatability . 41
6.10 Documentation . 42
Annex A (informative) Sound exposures and corresponding normalized 8 h-average
sound levels . 44
Annex B (informative) Relationship between tolerance interval, corresponding
acceptance interval and the maximum-permitted uncertainty of measurement . 45
Annex C (normative) Maximum-permitted uncertainties of measurement . 46
Annex D (informative) Example assessments of conformance to specifications of this
document . 47
D.1 General . 47
D.2 Conformance criteria . 47
D.3 Example test results. 47
Bibliography . 50

Figure B.1 – Relationship between tolerance interval, corresponding acceptance
interval and the maximum-permitted uncertainty of measurement . 45
Figure D.1 – Examples of assessment of conformance . 49

Table 1 – Acceptance limits for deviations of directional response from the design goal . 19
Table 2 – Reference response to a sequence of repeated 4 kHz tonebursts for time-
averaged non-equal-energy sound levels and acceptance limits . 22
Table A.1 – Sound exposures and corresponding normalized 8 h-average sound levels . 44
Table C.1 – Maximum-permitted uncertainties of measurement for a coverage
probability of 95 % for the response to short-duration signals for indications of time-
averaged non-equal-energy sound levels and for timing facilities . 46
Table D.1 – Examples of assessment of conformance . 48
IEC 61252:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Electroacoustics - Personal sound exposure meters

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61252 has been prepared by IEC technical committee 29: Electroacoustics. It is an
International Standard.
This second edition cancels and replaces the first edition published in 1993,
Amendment 1:2000, and Amendment 2:2017. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) personal sound exposure meters are required to provide indications of time-averaged sound
level and peak sound level;
b) sound exposure is an optional quantity for indication;
c) specifications for physical quantities that do not follow the principle of equal-energy
exchange rate have been added;
d) specifications for directional response have been added;
IEC 61252:2025 © IEC 2025
e) specifications for frequency weightings apply to the relative diffuse-field frequency
response;
f) determination of conformance to specifications takes account of uncertainties of
measurement;
g) detailed requirements for pattern-evaluation tests and periodic testing have been added.
The text of this International Standard is based on the following documents:
Draft Report on voting
29/1206/FDIS 29/1218/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IEC 61252:2025 © IEC 2025
INTRODUCTION
The principal application for a personal sound exposure meter is the measurement of sound
immission in the vicinity of a person's head, for example for assessment of occupational noise
exposure in accordance with International Standards such as ISO 1999 and ISO 9612.
The microphone of a personal sound exposure meter is typically worn on the shoulder, collar,
or other location close to the ear. In many practical situations, the sound immission indicated
by an instrument worn on a person is likely to be different from that which would be measured
in the absence of a person. The influence of the person wearing a personal sound exposure
meter should be considered when estimating the sound immission that would have been
measured with the person absent.
The most common physical quantities for characterisation of sound immission are time-
averaged sound levels and peak sound levels. For this reason, this document requires a
personal sound exposure meter to provide indications of these sound levels.
Other quantities which are sometimes measured include sound exposure and sound exposure
levels. Therefore, this document optionally allows a personal sound exposure meter to indicate
these quantities.
Sound exposure is a physical measure that accounts for both the sound pressure and its
duration, at a given location, through the time integral of the square of the instantaneous
frequency-weighted sound pressure. A doubling (or halving) of the integration time of a constant
sound level yields a doubling (or halving) of sound exposure. Similarly, an increase (or
decrease) of 3 dB in a constant input sound level for a constant integration time yields a
doubling (or halving) of the sound exposure. The same operating principle ("equal-energy
exchange rate") underlies the measurement of sound exposure level.
The term "dose" is sometimes used to refer to a percentage of a predetermined criterion for
exposure to noise in terms of a specified upper limit (often a legal limit) of a specified physical
quantity. The physical quantity and the value of the limit vary between jurisdictions, and some
jurisdictions specify quantities that are not based on the principle of equal-energy exchange.
Therefore, this document allows a personal sound exposure meter to indicate these quantities
and distinguishes between equal-energy-based and non-equal-energy-based quantities.
This document specifies performance requirements for personal sound exposure meters of one
performance class. The specifications generally correspond to those for a class 2 integrating-
averaging sound level meter as given in IEC 61672-1:2013 for an A-weighted sound pressure
level range at least from 67 dB to 137 dB and a nominal frequency range from 20 Hz to 8 kHz.
The design goals and the acceptance limits for deviations from the design goals are
representative of the performance of practical instruments. Personal sound exposure meters
are unlikely to be suitable for measurement of sound levels outside these ranges.
The title of this document has been changed with respect to IEC 61252:1993 because this
document includes requirements for pattern-evaluation tests and periodic testing in addition to
performance specifications.
The purpose of pattern evaluation is to determine whether a model of personal sound exposure
meter conforms to all the performance specifications given in this document.
The purpose of periodic testing is to assure the user that the individual personal sound exposure
meter conforms to the applicable performance specifications for a limited set of key tests and
for the environmental conditions under which the tests are performed. The extent of the periodic
tests is deliberately restricted to the minimum considered necessary. Because of the limited
extent of the periodic tests, evidence of pattern approval is necessary to state that the individual
personal sound exposure meter conforms to the complete set of specifications of this document.
The aim is to ensure that pattern evaluation and periodic testing are performed in a consistent
manner by all laboratories.
IEC 61252:2025 © IEC 2025
1 Scope
This document specifies
– performance specifications for personal sound exposure meters,
– details of the tests necessary to verify conformance to all mandatory specifications for the
purpose of pattern evaluation, and
– procedures for periodic testing of a personal sound exposure meter.
Personal sound exposure meters conforming to the requirements of this document have a
specified frequency response for sound incident on the microphone from all directions.
This document is applicable to instruments that are designed to be worn on a person in a
configuration specified by the manufacturer for the measurement of sound immission resulting
from steady, intermittent, fluctuating, irregular, or impulsive sounds. For reproducibility of
results, specifications and tests for the response to sound waves apply without an operator
present in the sound field.
Pattern evaluation tests and periodic tests described in this document apply to personal sound
exposure meters for which the manufacturer claims conformance to the specifications given in
this document.
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.
IEC 60942, Electroacoustics - Sound calibrators
IEC 61000-4-3:2020, Electromagnetic compatibility (EMC) - Part 4-3: Testing and measurement
techniques - Radiated, radio-frequency, electromagnetic field immunity test
IEC 61094-6, Measurement microphones - Part 6: Electrostatic actuators for determination of
frequency response
IEC 61183, Electroacoustics - Random-incidence and diffuse-field calibration of sound level
meters
IEC 61672 (all parts), Electroacoustics - Sound level meters
IEC 61672-1:2013, Electroacoustics - Sound level meters - Part 1: Specifications
IEC 61672-2:2013, Electroacoustics - Sound level meters - Part 2: Pattern evaluation tests
IEC 61672-3:2013, Electroacoustics - Sound level meters - Part 3: Periodic tests
IEC 62585:2012, Electroacoustics - Methods to determine corrections to obtain the free-field
response of a sound level meter
ISO/IEC Guide 98-3, Uncertainty of measurement - Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
ISO/IEC Guide 98-4, Uncertainty of measurement - Part 4: Role of measurement uncertainty in
conformity assessment
IEC 61252:2025 © IEC 2025
ISO/IEC Guide 99, International vocabulary of metrology - Basic and general concepts and
associated terms (VIM)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61000-4-3,
IEC 61183, IEC 61672 (all parts), IEC 62585, ISO/IEC Guide 98-3, ISO/IEC Guide 98-4,
ISO/IEC Guide 99, and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
sound exposure
time integral of the square of a frequency-weighted sound pressure signal over a stated time
interval or event of stated duration
Note 1 to entry: Duration of integration is included implicitly in the time integral and is not always reported explicitly,
although it is useful to state the nature of the event. For measurements of sound exposure over a specified time
interval, duration of integration is usually reported and indicated by a suitable subscript to the letter symbol, for
example as E .
A,1 h
Note 2 to entry: In symbols and as an example, A-weighted sound exposure E is represented by Formula (1):
A,T
t
E = p (t)dt
(1)
A,T A
∫
t
where pt is the square of the A-weighted sound-pressure signal during integration time T starting at t and
()
A 1
ending at t .
Note 3 to entry: The unit of sound exposure is pascal-squared seconds (Pa s) if sound pressure is in pascals and
running time is in seconds.
Note 4 to entry: For applications such as measurement of exposure to noise in the workplace, sound exposure in
pascal-squared hours is more convenient than pascal-squared seconds.
[SOURCE: IEC 61672-1:2013, 3.11]
3.2
normalized 8 h-average sound level
level of the time-mean-square, A-weighted sound pressure during a normalization time period
T of 8 h such that the sound exposure therefrom is equal to that of a time-varying sound at a
n
place where total sound exposure occurs within a time period not necessarily 8 h
Note 1 to entry: The unit of normalized 8 h-average sound level is decibels.
Note 2 to entry: In symbols, a normalized 8 h-average sound level (letter symbol L ), relative to the reference
Aeq,8 hn
sound pressure p and the 8 h normalization time period T , is related to sound exposure E in pascal-squared hours
0 n
by Formula (2):
 
L = 10lg E pT (2)
Aeq,8 hn ( 0 n)
 
 
or, alternatively, by Formula (3):
IEC 61252:2025 © IEC 2025
0,1×L
( )
2 Aeq,8 hn
E= pT 10 (3)
( )
0n 

Note 3 to entry: For computations, a simpler form of Formula (2) for normalized 8 h-average sound level is obtained,
for sound exposure E in pascal-squared hours, after substituting the values of 20 µPa for p and 8 h for T , as in
0 n
Formula (4):
 
LE10lg×10 3,2 (4)
( )
Aeq,8 hn
 
 
Note 4 to entry: When a total sound exposure is described indirectly by an A-weighted time-averaged sound
pressure level L , for an averaging time T greater or less than the normalization time period of 8 h, normalized
Aeq,T
8 h-average sound level can be determined from Formula (5):
L L +10lg(TT ) (5)
Aeq,8 hn Aeq,T n
Note 5 to entry: Annex A provides a table of normalized 8 h-average sound levels and corresponding sound
exposures. For example, a sound exposure of 1 Pa h (irrespective of the period of time over which it is measured)
corresponds to a normalized 8 h-average sound level of approximately 85 dB; a sound exposure of 3,20 Pa h
corresponds to a normalized 8 h-average sound level of 90 dB.
Note 6 to entry: Normalized 8 h-average sound level in Formula (2) is identical to "daily noise exposure level"
) defined in Directive 2003/10/EC, Article 2.
(L
EX,8h
Note 7 to entry: Normalized 8 h-average sound level in Formula (2) is also the same as "noise exposure level
normalized to a nominal 8 h working day, L " defined in ISO 1999.
EX,8 h
3.3
exchange rate
change in sound level corresponding to a doubling or halving of the duration of a steady input
sound pressure signal while a constant percentage non-equal-energy sound exposure is
maintained
3.4
non-equal-energy sound exposure
time integral of a power function of the time-weighted square of a frequency-weighted sound
pressure signal over a stated time interval or event of stated duration
Note 1 to entry: Duration of integration is included implicitly in the time integral and is not always reported explicitly,
although it is useful to state the nature of the event. For measurements of non-equal-energy sound exposure over a
specified time interval, duration of integration is usually reported and indicated by a suitable subscript to the letter
symbol, for example as E .
neeA,1 h
Note 2 to entry: In symbols and as an example, A-frequency weighted F-time weighted non-equal-energy sound
exposure E is represented by Formula (6):
neeAF,T
10lg(2) Q

t t
2 
  −(t−ξτ)
F

Ep= ξξed dt (6)
( )
 
neeAF,T A
∫∫τ
t −∞
 F


=
=
IEC 61252:2025 © IEC 2025
where
τ is the exponential time constant in seconds for time weighting F;
F
ξ is a dummy variable of time integration from some time in the past, as indicated by –∞ for the lower limit of
the integral, to the time of observation t;
pA(ξ) is the A-weighted instantaneous sound-pressure signal;
Q is the exchange rate in decibels;
T is the integration time beginning at t and ending at t .
1 2
Note 3 to entry: The unit of sound exposure is pascal-squared seconds (Pa s) if sound pressure is in pascals and
running time is in seconds.
Note 4 to entry: For applications such as measurement of exposure to noise in the workplace, sound exposure in
pascal-squared hours is more convenient than pascal-squared seconds.
Note 5 to entry: If the exchange rate were 3 dB and there were no time weighting, non-equal-energy sound exposure
would be equivalent to sound exposure.
3.5
criterion duration
specified duration of time integration
Note 1 to entry: The criterion duration is typically chosen to be the maximum duration of exposure for the
application, for example the duration of a working day.
3.6
criterion sound level
specified level of a sound
Note 1 to entry: The criterion sound level is typically chosen to be a level of sound which, if maintained for longer
than the criterion duration or if exceeded, could have adverse effects on human health.
3.7
criterion sound exposure
product of the criterion duration and the mean-square sound pressure corresponding to the
criterion sound level
Note 1 to entry: The criterion sound exposure is typically chosen to be a legal limit. Such limits vary between
jurisdictions and are subject to change.
3.8
criterion non-equal-energy sound exposure
product of the criterion duration and a power function of the mean-square sound pressure
corresponding to the criterion sound level
Note 1 to entry: The criterion non-equal-energy sound exposure is typically chosen to be a legal limit. Such limits
vary between jurisdictions and are subject to change.
3.9
percentage criterion sound exposure
quotient of sound exposure to criterion sound exposure, multiplied by 100
Note 1 to entry: The unit of percentage criterion sound exposure is per cent.
Note 2 to entry: In symbols and as an example, the percentage criterion sound exposure using frequency weighting
A can also be calculated from Formula (7):
t
0,1 LL−
2 ( )
A cr
DT= 100 10 dt
( ) (7)
A cr
∫
t
IEC 61252:2025 © IEC 2025
where
T is the criterion duration;
cr
T is the integration time beginning at t and ending at t ;
1 2
L is the A-frequency weighted sound level equivalent to the A-frequency-weighted input sound pressure;
A
L is the criterion sound level.
cr
3.10
percentage criterion non-equal-energy sound exposure
quotient of non-equal-energy sound exposure to criterion non-equal-energy sound exposure,
multiplied by 100
Note 1 to entry: The unit of percentage criterion non-equal-energy sound exposure is per cent.
Note 2 to entry: In symbols and as an example, the percentage criterion non-equal-energy sound exposure using
frequency weighting A and time weighting S can also be calculated from Formula (8):
t
LL− lg(2) Q
2 ( )( )
AS cr

DT= 100 10 dt (8)
( )
ASQ cr
∫
t
where
Q is the exchange rate in decibels;
T is the criterion duration;
cr
T is the integration time beginning at t and ending at t ;
1 2
L is the S-time-weighted A-frequency-weighted sound level equivalent to the A-frequency-weighted input sound
AS
pressure;
L is the criterion sound level.
cr
Note 3 to entry: If the exchange rate were 3 dB and there were no time weighting, percentage criterion non-equal-
energy sound exposure
...