Electroacoustics - Sound level meters -- Part 2: Pattern evaluation tests

Provides details of the tests necessary to verify conformance to all mandatory specifications given in EN 61672-1:2002 for conventional sound level meters, integrating-averaging sound level meters and integrating sound level meters. Pattern evaluation tests apply for each channel of a multi-channel sound level meter, as appropriate. Tests and test methods are applicable to class 1 and class 2 sound level meters. The aim is to ensure that all testing laboratories use consistent methods to perform pattern evaluation tests.

Elektroakustik - Schallpegelmesser -- Teil 2: Baumusterprüfungen

Electroacoustique - Sonomètres -- Partie 2: Essais d'évaluation d'un modèle

Donne des détails concernant les essais nécessaires permettant de vérifier la conformité à toutes les spécifications obligatoires données dans la EN 61672-1:2002 pour les sonomètres conventionnels, les sonomètres intégrateurs-moyenneurs, et les sonomètres intégrateurs. Les essais d'évaluation d'un modèle s'appliquent, comme il convient, à chaque canal d'un sonomètre à plusieurs canaux. Les essais et les méthodes d'essai sont applicables aux sonomètres de classe 1 et de classe 2. Le but est de s'assurer que tous les laboratoires d'essai utilisent des méthodes cohérentes pour effectuer les essais d'évaluation d'un modèle.

Electroacoustics - Sound level meters - Part 2: Pattern evaluation tests (IEC 61672-2:2003)

General Information

Status
Withdrawn
Publication Date
30-Jun-2004
Withdrawal Date
17-Feb-2021
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
18-Feb-2021
Due Date
13-Mar-2021
Completion Date
18-Feb-2021

Relations

Effective Date
06-May-2014
Effective Date
06-May-2014
Effective Date
06-May-2014
Effective Date
29-Jan-2023
Effective Date
29-Jan-2023
Effective Date
29-Jan-2023
Effective Date
07-Jun-2022
Effective Date
07-Jun-2022
Effective Date
07-Jun-2022

Buy Standard

Standard
EN 61672-2:2004
English language
44 pages
sale 10% off
Preview
sale 10% off
Preview
e-Library read for
1 day

Standards Content (Sample)

SLOVENSKI SIST EN 61672-2:2004

STANDARD
julij 2004
Electroacoustics - Sound level meters - Part 2: Pattern evaluation tests (IEC 61672-
2:2003)
ICS 17.140.50 Referenčna številka
SIST EN 61672-2:2004(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------

EUROPEAN STANDARD EN 61672-2
NORME EUROPÉENNE
EUROPÄISCHE NORM June 2003

ICS 17.140.50 Supersedes EN 60651:1994 + A1:1994 + A2:2001 & EN 60804:2000


English version


Electroacoustics –
Sound level meters
Part 2: Pattern evaluation tests
(IEC 61672-2:2003)


Electroacoustique –  Elektroakustik –
Sonomètres Schallpegelmesser
Partie 2: Essais d'évaluation d'un modèle Teil 2: Baumusterprüfungen
(CEI 61672-2:2003) (IEC 61672-2:2003)



This European Standard was approved by CENELEC on 2003-06-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61672-2:2003 E

---------------------- Page: 2 ----------------------

EN 61672-2:2003 - 2 -
Foreword

The text of document 29/532/FDIS, future edition 1 of IEC 61672-2, prepared by IEC TC 29,
Electroacoustics, in cooperation with the International Organization of Legal Metrology (OILM), was
submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61672-2 on
2003-06-01.

This European Standard, in conjunction with EN 61672-1, supersedes EN 60651:1994 + A1:1994 +
A2:2001 and EN 60804:2000.

The following dates were fixed:

– latest date by which the EN has to be implemented
 at national level by publication of an identical
 national standard or by endorsement (dop) 2004-03-01

– latest date by which the national standards conflicting
 with the EN have to be withdrawn (dow) 2006-06-01

Annexes designated "normative" are part of the body of the standard.
In this standard, annex A is normative.
Annex ZA has been added by CENELEC.
__________

Endorsement notice

The text of the International Standard IEC 61672-2:2003 was approved by CENELEC as a European Standard
without any modification.

__________

---------------------- Page: 3 ----------------------

- 3 - EN 61672-2:2003
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60942 - Electroacoustics - Sound calibrators EN 60942 2003

IEC 61000-4-2 1995 Electromagnetic compatibility (EMC) EN 61000-4-2 1995
Part 4-2: Testing and measurement
techniques - Electrostatic discharge
immunity test
A1 1998 A1 1998
A2 2000 A2 2001

IEC 61000-4-3 2002 Part 4-3: Testing and measurement EN 61000-4-3 2002
techniques - Radiated, radio-frequency,
electromagnetic field immunity test

IEC 61000-4-6 1996 Part 4-6: Testing and measurement EN 61000-4-6 1996
techniques - Immunity to conducted
disturbances, induced by radio-
frequency fields
A1 2000 A1 2001

IEC 61000-6-2 1999 Part 6-2: Generic standards - Immunity EN 61000-6-2 2001
(mod) for industrial environments

1) 2)
IEC 61094-1 - Measurement microphones EN 61094-1 2000
Part 1: Specifications for laboratory
standard microphones

1) 2)
IEC 61183 - Electroacoustics - Random-incidence EN 61183 1994
and diffuse-field calibration of sound
level meters

IEC 61672-1 2002 Electroacoustics - Sound level meters EN 61672-1 2003
Part 1: Specifications

1)
Undated reference.
2)
Valid edition at date of issue.

---------------------- Page: 4 ----------------------

EN 61672-2:2003 - 4 -
Publication Year Title EN/HD Year
CISPR 16-1 1999 Specification for radio disturbance and - -
immunity measuring apparatus and
methods
Part 1: Radio disturbance and immunity
measuring apparatus

CISPR 22 (mod) 1997 Information technology equipment - EN 55022 1998
Radio disturbance characteristics -
Limits and methods of measurement

ISO/IEC Guide 1995 Guide to the expression of uncertainty - -
Expres in measurement

ISO/IEC 1993 International vocabulary of basic and - -
general terms in metrology

---------------------- Page: 5 ----------------------

NORME CEI
INTERNATIONALE IEC
61672-2
INTERNATIONAL
Première édition
STANDARD
First edition
2003-04
Electroacoustique –
Sonomètres –
Partie 2:
Essais d'évaluation d'un modèle
Electroacoustics –
Sound level meters –
Part 2:
Pattern evaluation tests
© IEC 2003 Droits de reproduction réservés ⎯ Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
CODE PRIX
W
Commission Electrotechnique Internationale PRICE CODE
International Electrotechnical Commission
ɆɟɠɞɭɧɚɪɨɞɧɚɹɗɥɟɤɬɪɨɬɟɯɧɢɱɟɫɤɚɹɄɨɦɢɫɫɢɹ
Pour prix, voir catalogue en vigueur
For price, see current catalogue

---------------------- Page: 6 ----------------------

61672-2 © IEC:2003 – 3 –
CONTENTS
FOREWORD . 7
1 Scope .11
2 Normative references.11
3 Terms and definitions.13
4 Submission for testing.13
5 Marking of the sound level meter and information in the instruction manual .13
6 Mandatory facilities and general requirements .15
7 Environmental, electrostatic and radio-frequency tests .19
7.1 General .19
7.2 Expanded uncertainties for measurements of environmental test conditions .21
7.3 Influence of static pressure .21
7.4 Tolerance limits on air temperature, relative humidity and static pressure .23
7.5 Acclimatization requirements for tests of the influence of air temperature and
relative humidity.23
7.6 Abbreviated test of the influence of air temperature and relative humidity
combined.25
7.7 Influence of air temperature .29
7.8 Influence of relative humidity.31
7.9 Influence of electrostatic discharges.33
7.10 Influence of a.c. power frequency and radio-frequency fields .33
8 Radio-frequency emissions and public power supply disturbances .41
9 Electroacoustical performance tests .43
9.1 General .43
9.2 Indication at the calibration check frequency .43
9.3 Directional response .45
9.4 Tests of frequency weightings with acoustical signals .49
9.5 Tests of frequency weightings with electrical signals.55
9.6 Combined effect of reflections, diffraction and corrections for nominal
microphone frequency response and for the influence of a windscreen .59
9.7 Adjustments to obtain free-field sound levels.59
9.8 Level linearity.61
9.9 Under-range indication.65
9.10 Self-generated noise.65
9.11 Decay time constants for time weightings F and S .67
9.12 Toneburst response for sound level meters that measure time-weighted
sound level .67
9.13 Toneburst response for sound level meters that measure sound exposure
level or time-average sound level .69
9.14 Response to sequences of repeated tonebursts for sound level meters that
measure time-average sound level .71
9.15 Overload indication .73
9.16 Peak C sound level .75

---------------------- Page: 7 ----------------------

61672-2 © IEC:2003 – 5 –
9.17 Reset.77
9.18 Electrical output .77
9.19 Timing facilities.77
9.20 Crosstalk in multi-channel sound level meter systems .77
9.21 Power supply .77
10 Pattern evaluation report .79

---------------------- Page: 8 ----------------------

61672-2 © IEC:2003 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTROACOUSTICS – SOUND LEVEL METERS –
Part 2: Pattern evaluation tests
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61672-2 has been prepared by IEC technical committee 29:
Electroacoustics, in cooperation with the International Organization of Legal Metrology (OIML).
This standard, in conjunction with IEC 61672-1, cancels and replaces IEC 60651 (1979) and
IEC 60804 (2000).
The text of this standard is based on the following documents:
FDIS Report on voting
29/532/FDIS 29/538/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
At the time of publication of this standard, the IEC 61672 series was scheduled to consist at
least of the following parts under the general title Electroacoustics – Sound level meters:
Part 1: Specifications
Part 2: Pattern evaluation tests
Part 3: Periodic tests

---------------------- Page: 9 ----------------------

61672-2 © IEC:2003 – 9 –
The committee has decided that the contents of this publication will remain unchanged until
2005. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.

---------------------- Page: 10 ----------------------

61672-2 © IEC:2003 – 11 –
ELECTROACOUSTICS – SOUND LEVEL METERS –
Part 2: Pattern evaluation tests
1 Scope
This part of IEC 61672 provides details of the tests necessary to verify conformance to all
mandatory specifications given in IEC 61672-1:2002 for conventional sound level meters,
integrating-averaging sound level meters and integrating sound level meters. Pattern
evaluation tests apply for each channel of a multi-channel sound level meter, as appropriate.
Tests and test methods are applicable to class 1 and class 2 sound level meters. The aim is to
ensure that all testing laboratories use consistent methods to perform pattern evaluation tests.
2 Normative references
The following referenced documents are indispensable for the application 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 61000-4-2:2001, Electromagnetic compatibility (EMC) – Part 4-2: Testing and measure-
1
ment techniques – Electrostatic discharge immunity test – Basic EMC Publication
IEC 61000-4-3:2002, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measure-
ment techniques – Radiated, radio-frequency, electromagnetic field immunity test – Basic EMC
2
Publication
IEC 61000-4-6:2001, Electromagnetic compatibility (EMC) – Part 4-6: Testing and measure-
ment techniques – Immunity to conducted disturbances, induced by radio-frequency fields –
3
Basic EMC Publication
IEC 61000-6-2:1999, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61094-1, Measurement microphones – Part 1: Specifications for laboratory standard
microphones
IEC 61183, Electroacoustics – Random-incidence and diffuse-field calibration of sound level
meters
IEC 61672-1:2002, Electroacoustics – Sound level meters – Part 1: Specifications
___________
1
Edition 1.2 consisting of Edition 1:1995 consolidated with amendments 1:1998 and 2:2000.
2
Edition 2.1 consisting of Edition 2:2002 consolidated with amendment 1:2002.
3
Edition 1.1 consisting of Edition 1:1996 consolidated with amendment 1:2000.

---------------------- Page: 11 ----------------------

61672-2 © IEC:2003 – 13 –
CISPR 16-1:1999, Specification for radio disturbance and immunity measuring apparatus and
4
methods – Part 1: Radio disturbance and immunity measuring apparatus
CISPR 22:1997, Information technology equipment – Radio disturbance characteristics – Limits
and methods of measurement
ISO Express Guide, Guide to the expression of uncertainty in measurement
ISO/IEC, International vocabulary of basic and general terms in metrology
3 Terms and definitions
For the purposes of this standard, in addition to the terms and definitions given in IEC 61672-1,
the terms and definitions given in IEC 61000-4-2:2001, IEC 61000-4-3:2002, IEC
61000-4-6:2001, the Guide to the expression of uncertainty in measurement and the
International vocabulary of basic and general terms in metrology also apply.
4 Submission for testing
4.1 At least three specimens of the same pattern of sound level meter shall be submitted for
pattern evaluation testing. As a minimum, the testing laboratory shall select two of the
specimens for testing. At least one of the two specimens shall then be tested fully according to
the procedures of this standard. The testing laboratory shall decide whether the full tests shall
also be performed on the second specimen or whether limited testing is adequate to approve
the pattern.
4.2 An instruction manual and all items or accessories that are identified in the instruction
manual as integral components for the normal mode of operation shall be submitted along with
the sound level meters. Examples of additional items or accessories include a microphone
extension device or cable and peripheral equipment.
4.3 If the manufacturer of the sound level meter supplies devices that are to be connected to
the sound level meter by cables, then the devices and cables shall be submitted with the sound
level meter.
4.4 A calibrated sound calibrator of a model specified in the instruction manual for the sound
level meter shall be supplied with the sound level meter. An instruction manual for the sound
calibrator shall also be provided. The model of the calibrator shall conform to the specifications
of IEC 60942 for the class, as required by 5.2.2 of IEC 61672-1:2002.
5 Marking of the sound level meter and information
in the instruction manual
5.1 It shall be verified that the sound level meter is marked according to the requirements of
Clause 8 of IEC 61672-1:2002.
5.2 Before conducting any tests, it shall be verified that the instruction manual contains all the
information that is required by Clause 9 of IEC 61672-1:2002 as relevant to the facilities
provided by the sound level meter.
___________
4
In English, CISPR stands for International Special Committee on Radio Interference.

---------------------- Page: 12 ----------------------

61672-2 © IEC:2003 – 15 –
5.3 If the sound level meter does not conform to the requirements of 5.1 and 5.2, no pattern
evaluation tests shall be performed.
5.4 After completion of all tests, the information shall be reviewed to ensure that it is correct
within the appropriate tolerance limits.
6 Mandatory facilities and general requirements
6.1 No test specified in this part of IEC 61672 shall be omitted unless the sound level meter
does not possess the facility described for the test.
NOTE Where the design of a sound level meter, which has been pattern approved, is changed and a new pattern
approval is requested, then, at the discretion of the testing laboratory, it is not necessary to repeat those tests for
electroacoustical performance characteristics that are not affected by the design change.
6.2 A conventional sound level meter shall be verified to be able to display A-frequency-
weighted and F-time-weighted sound level, and to be able to indicate overload and under-range
conditions, if applicable.
6.3 An integrating-averaging sound level meter shall be verified to be able to display
A-weighted time-average sound level, and to be able to indicate overload and under-range
conditions, if applicable.
6.4 An integrating sound level meter shall be verified to be able to display A-weighted sound
exposure level, and to be able to indicate overload and under-range conditions, if applicable.
6.5 All display devices for the sound level meter shall be verified to be able to display sound
levels or sound exposure levels with the resolution required by 5.15.3 of IEC 61672-1:2002.
The range of the display shall be at least the minimum specified in 5.15.3 of IEC 61672-1:2002.
6.6 Where a sound level meter is capable of measuring maximum or peak sound levels, or
both, it shall be verified that a “hold” feature is provided.
6.7 A class 1 sound level meter shall be verified to have frequency-weighting C, at least for
pattern evaluation testing.
6.8 If the sound level meter is capable of indicating peak C sound levels, it shall be verified
that the capability to display C-weighted, time-weighted sound level or C-weighted, time-
average sound level is also provided, at least for pattern evaluation testing.
6.9 For sound level meters with multiple level ranges, it shall be verified that the level range
overlap conforms to the specifications of 5.5.8 of IEC 61672-1:2002.
6.10 For sound level meters that can display more than one measurement quantity, it shall be
verified that there is a clear means to ascertain the quantity that is being displayed.
6.11 If the sound level meter does not possess the mandatory facilities listed in 6.2
through 6.10, as applicable, the sound level meter does not conform to the specifications of
IEC 61672-1:2002 and no pattern evaluation tests shall be performed.

---------------------- Page: 13 ----------------------

61672-2 © IEC:2003 – 17 –
6.12 For all pattern evaluation tests, the configuration of the sound level meter, or the multi-
channel sound level meter system, shall be as specified in the instruction manual for one of the
normal modes of operation, including required accessories. The configuration shall include a
windscreen if a windscreen is an integral component for the normal mode of operation, or if the
instruction manual states that the sound level meter conforms to the specifications of
IEC 61672-1 with a windscreen installed around the microphone. The model of the windscreen
shall be as stated in the instruction manual for use with the sound level meter. All
configurations of the sound level meter that are stated in the instruction manual as conforming
to the requirements of IEC 61672-1 shall be tested.
6.13 If the instruction manual states that the sound level meter conforms to the specifications
of IEC 61672-1 with optional facilities installed, the combination with the optional facilities
installed shall also be tested to verify conformance to the relevant specifications.
6.14 If an electrical output is provided on the sound level meter and the testing laboratory
intends to utilize the electrical output instead of the display device, the laboratory shall verify
that changes in the levels of applied acoustical or electrical input signals produce changes in
the signal levels indicated on the display device and at the electrical output in accordance
with 5.16.3 of IEC 61672-1:2002. This requirement applies to each channel of a multi-channel
system.
NOTE Where multiple outputs are present, if an output is specified in the instruction manual for testing, this output
should be used for the pattern evaluation tests.
6.15 For all tests, the sound level meter shall be powered from its preferred supply. If the
instruction manual specifies internal batteries of a particular type, such batteries shall be
installed for the pattern evaluation tests.
6.16 The sound level meter shall be allowed to reach equilibrium with the prevailing
environmental conditions before switching on the power to perform a test.
6.17 Tests for conformance to the specifications for the effects of changes in environmental
conditions preferably should be conducted before tests for conformance to the specifications
for electroacoustical performance.
6.18 If the sound level meter has more than one signal-processing channel, pattern
evaluation tests shall be performed for each channel that utilizes unique signal processing
techniques. For multi-channel systems with the same functional equivalence in all channels,
the number of channels to be tested may be less than the number of channels, at the discretion
of the testing laboratory.
NOTE 1 For a multi-channel system, the number of channels to be tested should be determined from
consideration of a scenario for which there is an array of microphones supplying signals to each input with each
channel processing the signals in an identical manner. Selection of how many and which channels to test should
consider differences, as described in the instruction manual, in the implementation of signal-processing techniques
in the various channels.
NOTE 2 If the sound level meter is a multi-channel device (for example, a sound level meter with two or more
separate signal inputs with non-parallel processing of digitized data by time-sharing, but quasi-parallel display for
the displayed signals), it should be possible to test the channels for identical functionality either by setting the
functions of the channels for identical processing and reading the display(s) or by allowing the channel functionality
to rotate by a special test setting procedure thereby allowing comparison of display(s).
6.19 Conformance to the specifications of IEC 61672-1 is verified when measured deviations
from design goals, extended by the actual expanded uncertainties of measurement of the
testing laboratory, lie fully within the applicable tolerance limits. A positive value for a
measured extended deviation shall be not greater than the corresponding positive tolerance
limit. A negative value for a measured extended deviation shall be not less than the
corresponding negative tolerance limit.

---------------------- Page: 14 ----------------------

61672-2 © IEC:2003 – 19 –
6.20 The testing laboratory shall use instruments with current calibrations for the appropriate
quantities. The calibrations shall be traceable to national standards, as required.
6.21 Laboratories performing pattern evaluation tests shall calculate all uncertainties of
measurements in accordance with the guidelines given in the Guide to the expression of
uncertainty in measurement. Metrological terms are defined in the International vocabulary
of basic and general terms in metrology. Actual expanded uncertainties shall be calculated for
a level of confidence of 95 %, using the necessary coverage factor.
NOTE 1 When a testing laboratory is only required to perform a single measurement, it is necessary for the
laboratory to make an estimate of the random contribution to the total measurement uncertainty. The estimate may
be determined from an earlier evaluation of several measurements for a similar sound level meter.
NOTE 2 Generally a coverage factor of 2 approximates to a level of confidence of 95 %, unless the contributions
are such that it is necessary to use a different coverage factor to maintain the 95 % level of confidence.
6.22 The actual expanded uncertainties of measurement shall n
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.