EN 61672-2:2003

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
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

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
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.
__________
- 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.

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
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
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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.
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Pour prix, voir catalogue en vigueur
For price, see current catalogue

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

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

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
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.
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-
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
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 –
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
___________
Edition 1.2 consisting of Edition 1:1995 consolidated with amendments 1:1998 and 2:2000.
Edition 2.1 consisting of Edition 2:2002 consolidated with amendment 1:2002.
Edition 1.1 consisting of Edition 1:1996 consolidated with amendment 1:2000.

61672-2 © IEC:2003 – 13 –
CISPR 16-1:1999, Specification for radio disturbance and immunity measuring apparatus and
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.
___________
In English, CISPR stands for International Special Committee on Radio Interference.

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.

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.

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 not exceed the corresponding
maximum expanded uncertainties of measurement from Annex A of IEC 61672-1:2002. When
this condition is not achieved, the result of the test shall not be used to demonstrate
conformance to a specification and pattern approval shall not be granted.
NOTE Calculation of the expanded uncertainty of measurement for a particular test should consider at least five
components. The first component is the uncertainty attributed to calibration of the individual instruments and
equipment used to perform the test, including the sound calibrator, where applicable. The second component is any
contribution resulting from environmental effects or adjustments. The third component is any small errors that may
be present in the applied signals and are considered as uncertainties. The fourth component is any random
uncertainty attributed to repeated measurements and dependent on the characteristics of the sound level meter
under test. The fifth component is, where applicable, an uncertainty contribution for reading the indication from the
display device of the sound level meter under test. For digital display devices that indicate signal levels with a
resolution of 0,1 dB, the uncertainty component should be taken as a rectangular distribution with semi-range of
0,05 dB.
6.23 For legal metrology purposes, the tolerance limits around the design goals specified in
IEC 61672-1 shall be considered to be the maximum permissible errors for pattern evaluation,
initial verification and subsequent verification.
7 Environmental, electrostatic and radio-frequency tests
7.1 General
7.1.1 Before conducting, but not during, the tests described in the various subclauses of
Clause 7, the indication at the calibration check frequency shall be checked by application of
the sound calibrator specified in 4.4 and adjusted, if necessary, to indicate the required sound
pressure level under reference environmental conditions. The adjustment shall use the
procedure given in the instruction manual for the sound level meter. For multi-channel devices,
the corresponding indications shall be checked for all channels selected for testing.
7.1.2 Environmental conditions at the time of checking the indication shall be recorded.
7.1.3 The effect of environmental conditions on the sound pressure level produced by the
sound calibrator shall be accounted for in accordance with the procedure in the instruction
manual for the sound calibrator and data from its calibration. The effects shall be evaluated
relative to the sound pressure level produced under reference conditions.

61672-2 © IEC:2003 – 21 –
7.1.4 For environmental tests, a sound calibrator shall be used to provide a signal of known
sound pressure level at the microphone of the sound level meter. The sound calibrator shall be
a class 1 device as specified in IEC 60942. The effects of static pressure, air temperature and
relative humidity on the sound pressure level produced in the coupler of the sound calibrator,
over the range of environmental conditions specified for the tests, shall be known.
NOTE A class LS sound calibrator as specified in IEC 60942 may be used if the effects of static pressure, air
temperature and relative humidity, as applicable, on the sound pressure level produced in the coupler of the sound
calibrator, over the range of environmental conditions specified for these tests, are known. It should be noted that
the range of environmental conditions specified for these tests exceeds the range specified in IEC 60942 for class
LS sound calibrators.
7.1.5 The sound level meter shall be set to perform a typical measurement of time-weighted
sound level, time-average sound level or sound exposure level on the reference level range.
The frequency weighting shall be set to A weighting. F-time-weighted sound level or time-
average sound level is preferred.
7.1.6 Time-weighted sound levels, time-average sound levels or sound exposure levels
indicated by the sound level meter in response to the signal from the sound calibrator shall be
recorded for each test condition. Where necessary, time-average sound levels shall be
calculated in accordance with Equation (5b) of IEC 61672-1:2002 from the indications of sound
exposure level and elapsed time. Averaging times for time-average sound levels or integration
times for sound exposure levels shall be recorded.
7.2 Expanded uncertainties for measurements of environmental test conditions
The actual expanded uncertainty of measurement shall not exceed 0,2 kPa for measurements
of static pressure. The actual expanded uncertainty of measurement shall not exceed 0,3 °C
and 4 % relative humidity for measurements of air temperature and relative humidity,
respectively.
7.3 Influence of static pressure
7.3.1 During the measurements of the influence of static pressure, air temperature shall be
maintained within ±2,3 K (±2,3° C) of the reference air temperature. Relative humidity at the
reference static pressure shall be maintained within +24 % relative humidity to –14 % relative
humidity of the reference relative humidity. The variation limits refer to the measured air
temperatures and relative humidities with allowance for measurement uncertainty from 7.2.
7.3.2 For practical reasons, relative humidity is specified for the reference static pressure.
Evacuating or pressurizing an enclosure around a sound level meter will change the relative
humidity within the enclosure. No corrections for this effect shall be applied.
7.3.3 The influence of static pressure shall be tested at the reference static pressure and at
seven other static pressures. At each static pressure, the sound calibrator of 7.1.4 and the
sound level meter (or its relevant components) shall be permitted to acclimatize for at least
10 min before recording the indicated sound level. For tests of the influence of static pressure,
the sound calibrator shall remain coupled to the microphone of the sound level meter during
the acclimatization periods. The power to the sound level meter may be on continuously, or
may be switched off and on by remote means.

61672-2 © IEC:2003 – 23 –
7.3.4 Sound levels shall be measured twice at nominal static pressures spaced at
approximately equal intervals between the minimum and the maximum static pressure
specified in 6.2 of IEC 61672-1:2002. For each nominal static pressure condition, the two
measured static pressures shall be the same within 1 kPa. One measurement sequence shall
start from the minimum static pressure and increase to each selected nominal pressure until
the maximum is reached. The other sequence shall follow a decrease in pressure from the
maximum via each of the selected nominal pressures until the minimum is reached. At the
maximum static pressure, only one indication of sound level shall be recorded.
7.3.5 The indicated sound levels shall be corrected for any difference between the sound
pressure level generated by the sound calibrator under the test condition and the sound
pressure level generated under reference environmental conditions.
7.3.6 At each static pressure test condition, the deviation of the indicated sound level from
the sound level first indicated at the reference static pressure shall be extended by the actual
expanded uncertainty of measurement. Each extended deviation shall be within the applicable
tolerance limits specified in 6.2 of IEC 61672-1:2002.
7.4 Tolerance limits on air temperature, relative humidity and static pressure
Unless specified otherwise, for each test of the influence of air temperature and relative
humidity, including the acclimatization requirements given in 7.5, the air temperature shall be
within ±1,3 K (±1,3 °C) of a specified air temperature, the relative humidity shall be within ±9 %
relative humidity of a specified relative humidity, and the difference between the maximum and
minimum values of the prevailing static pressure shall not exceed 6,2 kPa. The variation limits
refer to the measured air temperatures, relative humidities and static pressure with allowance
for measurement uncertainties from 7.2.
7.5 Acclimatization requirements for tests of the influence of air temperature and
relative humidity
7.5.1 The sound calibrator of 7.1.4 and the sound level meter (or relevant components) shall
be placed in an environmental chamber to test the influence of air temperature and relative
humidity on the sound level meter.
7.5.2 For tests of the influence of air temperature and relative humidity, the sound calibrator
and the microphone on the sound level meter shall be uncoupled and the power to both
instruments switched off during an acclimatization period.
7.5.3 The sound calibrator and sound level meter shall be permitted to acclimatize at the
reference environmental conditions for at least 12 h.
7.5.4 For all test conditions other than reference environmental conditions, the sound
calibrator and sound level meter shall be permitted to acclimatize for at least an additional 7 h
after completion of the initial 12 h acclimatization period, unless the testing laboratory has
applicable evidence that a shorter acclimatization period is sufficient.
7.5.5 After completion of an acclimatization period, the sound calibrator shall be coupled to
the microphone of the sound level meter and the power switched on to both instruments.

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7.5.6 The testing laboratory may have the facility to couple the sound calibrator to the
microphone of the sound level meter without affecting the temperature and relative humidity in
the environmental test chamber. If this facility is available, sound levels may be recorded
following the time specified in the instruction manual for pressure equalization of the
microphone. If this facility is not available, at least a further 3 h acclimatization time shall be
allowed before commencing a test.
7.6 Abbreviated test of the influence of air temperature
and relative humidity combined
7.6.1 To reduce the time and cost of verifying the influence of air temperature and relative
humidity on the performance of a sound level meter, a set of abbreviated tests shall first be
performed for certain combinations of air temperature and relative humidity.
7.6.2 For the abbreviated tests of the influence of air temperature and relative humidity
combined, the tolerance limits are smaller than those specified in 6.3 and 6.4 of
IEC 61672-1:2002. If the sound level meter conforms within the reduced tolerance limits at all
specified test conditions, then the sound level meter shall be considered to fully conform to the
specifications of 6.3 and 6.4 of IEC 61672-1:2002. No additional tests are required. If the
sound level meter fails to conform within the reduced tolerance limits for any specified
test condition, then additional temperature and humidity tests shall be performed to determine
conformance to the specifications of IEC 61672-1. The additional tests are described in 7.7
and 7.8.
7.6.3 Following the acclimatization procedures described in 7.5, the sound level indicated in
response to application of the sound calibrator of 7.1.4 shall be recorded for certain
combinations of air temperature and relative humidity.
NOTE 1 When setting the test conditions, rapid changes of air temperature in the test chamber should be avoided.
NOTE 2 Care should be taken to avoid condensation while the temperature is being changed in the environmental
test chamber.
NOTE 3 It is important to monitor the relative humidity in the environmental test chamber each time the air
temperature is changed to ensure that it remains within the specified tolerance limits.
NOTE 4 The indicated combinations of temperature and relative humidity were chosen in consideration of the
dewpoints that were obtainable within available environmental test facilities. The combinations also reflect the
range of environmental conditions for general applications of class 1 and class 2 sound level meters.
7.6.4 For sound level meters where all components can be operated over the wide range of
air temperature and relative humidity covered by the specifications in 6.3 and 6.4 of IEC
61672-1:2002, the target test conditions are:
• for class 1:
⎯ reference air temperature and reference relative humidity,
⎯ air temperature of –10 °C and relative humidity of 65 %,
⎯ air temperature of +5 °C and relative humidity of 25 %,
⎯ air temperature of +40 °C and relative humidity of 90 %, and
⎯ air temperature of +50 °C and relative humidity of 50 %.

61672-2 © IEC:2003 – 27 –
• for class 2:
⎯ reference air temperature and reference relative humidity,
⎯ air temperature of 0 °C and relative humidity of 30 %, and
⎯ air temperature of +40 °C and relative humidity of 90 %.
7.6.5 For those components of a sound level meter that are designated in the instruction
manual as intended only for operation in an environmentally controlled enclosure, the target
test conditions are:
⎯ reference air temperature and reference relative humidity,
⎯ air temperature of +5 °C and relative humidity of 25 %, and
⎯ air temperature of +35 °C and relative humidity of 80 %.
7.6.6 For sound level meters that consist of combinations of components, the abbreviated
environmental tests shall be performed in three steps.
• In step 1, the components that can be operated over a wide range of environmental
conditions (for example, a microphone and preamplifier) and the components that operate
only in the controlled environment (for example, a computer) shall be exposed to the
reference environmental conditions.
• In step 2, the wide-range components shall be exposed to the combinations of
environmental conditions of 7.6.4 (four conditions for class 1 or two conditions for class 2
sound level meters) while the controlled-environment components are maintained at
reference environmental conditions.
• In step 3, the controlled-environment components shall be exposed to the two combinations
of environmental conditions of 7.6.5, while the wide-range components are maintained at
reference environmental conditions.
For each test condition, the acclimatization procedure of 7.5 shall be followed. The sound
levels indicated in response to application of the sound calibrator shall be recorded.
NOTE In step 3, when the microphone is exposed to reference environmental conditions, an equivalent electrical
input signal may be substituted for the acoustical signal from the sound calibrator if necessary to ensure that the
actual expanded uncertainty of measurement remains less than the maximum allowed expanded uncertainty.
7.6.7 For all tests, the indicated sound levels shall be corrected for any difference between
the sound pressure level generated by the sound calibrator under the test conditions and the
sound pressure level generated
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