EN 61672-1:2003

SLOVENSKI SIST EN 61672-1:2004

STANDARD
julij 2004
Electroacoustics - Sound level meters - Part 1: Specifications (IEC 61672-1:2002)
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 61672-1
NORME EUROPÉENNE
EUROPÄISCHE NORM February 2003

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

English version
Electroacoustics -
Sound level meters
Part 1: Specifications
(IEC 61672-1:2002)
Electroacoustique -  Elektroakustik -
Sonomètres Schallpegelmesser
Partie 1: Spécifications Teil 1: Anforderungen
(CEI 61672-1:2002) (IEC 61672-1:2002)

This European Standard was approved by CENELEC on 2003-02-01. 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 61672-1:2003 E
Foreword
The text of document 29/507/FDIS, future edition 1 of IEC 61672-1, 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 61672-1 on
2003-02-01.
This European Standard, in conjunction with EN 61672-2, 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) 2003-11-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-02-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes A and ZA are normative and annexes B and C are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61672-1:2002 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 standards
indicated:
IEC 61012 NOTE Harmonized as EN 61012:1998 (not modified).
IEC 61252 NOTE Harmonized as EN 61252:1995 (not modified).
IEC 60651 NOTE Harmonized as EN 60651:1994 (not modified).
IEC 60804 NOTE Harmonized as EN 60804:2000 (not modified).
__________
- 3 - EN 61672-1:2003
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
CISPR 16-1 1999 Specification for radio disturbance - -
and immunity measuring apparatus
and methods
Part 1: Radio disturbance
and immunity measuring apparatus

1)
IEC 60050-801 - International Electrotechnical - -
Vocabulary (IEV)
Chapter 801: Acoustics and
electroacoustics
1)
IEC 60942 - Electroacoustics - Sound calibrators - -

1)
2)
IEC 61000-4-2 - Electromagnetic compatibility (EMC) EN 61000-4-2 1995
Part 4-2: Testing and measurement
techniques - Electrostatic discharge
immunity test
IEC 61000-6-2 1999 Part 6-2: Generic standards - Immunity EN 61000-6-2 2001
(mod) for industrial environments

ISO/IEC GUIDE 1995 Guide to the expression of uncertainty - -
EXPRES in measurement (GUM)
1)
ISO Publication - International vocabulary of basic and - -
ISBN 92-67- general terms in metrology
01075-1
1)
Undated reference.
2)
Valid edition at date of issue.

NORME CEI
INTERNATIONALE IEC
61672-1
INTERNATIONAL
Première édition
STANDARD
First edition
2002-05
Electroacoustique –
Sonomètres –
Partie 1:
Spécifications
Electroacoustics –
Sound level meters –
Part 1:
Specifications
© IEC 2002 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.
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Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
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Pour prix, voir catalogue en vigueur
For price, see current catalogue

61672-1 © IEC:2002 – 3 –
CONTENTS
FOREWORD.5
1 Scope.9
2 Normative references .11
3 Terms and definitions .11
4 Reference environmental conditions .21
5 Performance specifications.21
5.1 General .21
5.2 Adjustments to indicated levels .27
5.3 Directional response.29
5.4 Frequency weightings.31
5.5 Level linearity.39
5.6 Self-generated noise .41
5.7 Time weightings F and S .41
5.8 Toneburst response.43
5.9 Response to repeated tonebursts .47
5.10 Overload indication .47
5.11 Under-range indication .49
5.12 Peak C sound level .49
5.13 Reset .51
5.14 Thresholds .51
5.15 Display.51
5.16 Analogue or digital output.53
5.17 Timing facilities .53
5.18 Radio frequency emissions and disturbances to a public power supply.53
5.19 Crosstalk.55
5.20 Power supply.55
6 Environmental, electrostatic, and radio frequency criteria .57
6.1 General .57
6.2 Static pressure .57
6.3 Air temperature .57
6.4 Humidity.59
6.5 Electrostatic discharge .59
6.6 AC power frequency and radio frequency fields .59
7 Provision for use with auxiliary devices .63
8 Marking .63
9 Instruction manual .65
Annex A (normative) Maximum expanded uncertainties of measurement .75
Annex B (informative) AU weighting.77
Annex C (informative) Specifications for time-weighting I (impulse).79
Bibliography.85

61672-1 © IEC:2002 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTROACOUSTICS – SOUND LEVEL METERS –
Part 1: Specifications
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 cooperation 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 informational 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 61672-1 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 61672-2, cancels and replaces IEC 60651, Sound level
meters, and IEC 60804, Integrating-averaging sound level meters.
The text of this standard is based on the following documents:
FDIS Report on voting
29/507/FDIS 29/515/RVD
Full information on the voting for the approval of this standard can be found in the report of
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
Annex A forms an integral part of this standard.
Annexes B and C are for information only.
At the time of publication of this standard, the IEC 61672 series was scheduled to consist at
least of the following parts: IEC 61672-1: Specifications, IEC 61672-2: Pattern evaluation
tests, and IEC 61672-3: Periodic tests.

61672-1 © IEC:2002 – 7 –
The committee has decided that the contents of IEC 61672-1 will remain unchanged until
2005. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61672-1 © IEC:2002 – 9 –
ELECTROACOUSTICS – SOUND LEVEL METERS –
Part 1: Specifications
1 Scope
1.1 This standard gives electroacoustical performance specifications for three kinds of
sound measuring instruments:
– a conventional sound level meter that measures exponential time-weighted sound level;
– an integrating-averaging sound level meter that measures time-average sound level; and
– an integrating sound level meter that measures sound exposure level.
A single instrument may make any, or all, of the three kinds of measurements. Additional
performance specifications are given for the measurement of maximum time-weighted sound
level and peak C sound level. Frequency-weighting A is mandatory for all sound level meters
specified in this standard.
1.2 Sound level meters conforming to the requirements of this standard have a specified
frequency response for sound incident on the microphone from one principal direction in an
acoustic free field or from random directions.
1.3 Sound level meters specified in this standard are intended to measure sounds generally
in the range of human hearing.
NOTE For measurement of audible sound in the presence of ultrasound, the AU weighting, specified in IEC 61012
[1], may be applied.
1.4 Two performance categories, class 1 and class 2, are specified in this standard. In
general, specifications for class 1 and class 2 sound level meters have the same design goals
and differ mainly in the tolerance limits and the range of operational temperatures. Tolerance
limits for class 2 specifications are greater than, or equal to, those for class 1 specifications.
1.5 This standard is applicable to a range of designs for sound level meters. A sound level
meter may be a self-contained hand-held instrument with an attached microphone and a built-
in display device. A sound level meter may be comprised of separate components in one or
more enclosures and may be capable of displaying a variety of acoustical signal levels. Sound
level meters may include extensive analogue or digital signal processing, separately or in
combination, with multiple analogue and digital outputs. Sound level meters may include
general-purpose computers, recorders, printers, and other devices that form a necessary part
of the complete instrument.
———————
Numbers in square brackets refer to the bibliography.

61672-1 © IEC:2002 – 11 –
1.6 Sound level meters may be designed for use with an operator present or for automatic
and continuous measurements of sound level without an operator present. Specifications in
this standard for the response to sound waves apply without an operator present in the sound
field.
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.
CISPR 16-1:1999, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1: Radio disturbance and immunity measuring apparatus
IEC 60050(801), International Electrotechnical Vocabulary – Chapter 801: Acoustics and
electroacoustics
IEC 60942, Electroacoustics – Sound calibrators
IEC 61000-4-2, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 2: Electrostatic discharge immunity test. Basic EMC Publication
IEC 61000-6-2:1999, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
ISO/IEC GUIDE EXPRES:1995, Guide to the expression of uncertainty in measurement
ISO Publication, ISBN 92-67-01075-1, International vocabulary of basic and general terms in
metrology
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in IEC 60050(801), the
International vocabulary of basic and general terms in metrology, the Guide to the expression
of uncertainty in measurement, and IEC 61000-6-2:1999, as well as the following apply. All
quantities are expressed in Sl units.
3.1
reference sound pressure
reference quantity conventionally chosen equal to 20 µPa for airborne sound
3.2
sound pressure level
twenty times the logarithm to the base ten of the ratio of the root-mean-square of a given
sound pressure to the reference sound pressure
NOTE Sound pressure level is expressed in decibels (dB); symbol L .
p
———————
In English, CISPR stands for International Special Committee on Radio Interference.

61672-1 ” IEC:2002 – 13 –
3.3
frequency weighting
for a sound level meter, the difference between the level of the signal indicated on the display
device and the corresponding level of a constant-amplitude steady-state sinusoidal input
signal, specified in this standard as a function of frequency
NOTE The difference in level is expressed in decibels (dB).
3.4
time weighting
exponential function of time, of a specified time constant, that weights the square of the
instantaneous sound pressure
3.5
time-weighted sound level
twenty times the logarithm to the base ten of the ratio of a given root-mean-square sound
pressure to the reference sound pressure, root-mean-square sound pressure being obtained
with a standard frequency weighting and standard time weighting
NOTE 1 Time-weighted sound level is expressed in decibels (dB).
NOTE 2 For time-weighted sound level, example letter symbols are L , L , L , and L for frequency
AF AS CF CS
weightings A and C and time weightings F and S.
NOTE 3 In symbols, A-weighted and time-weighted sound level, L (t), at any instant of time t is represented by
AW
1/ 2
­½t
°°
ªº2(t[W)/
Lt() 20 lg1/W[pe d[ p (1)
®¾
AAW 0
³
«»f
¬¼
°°
¯¿
where
– W is the exponential time constant in seconds for time weighting F or S;
– [ is a dummy variable of time integration from some time in the past, as indicated by -f for the lower limit of
the integral, to the time of observation t;
– p ([) is the A-weighted instantaneous sound pressure; and
A
– p is the reference sound pressure.
In equation (1), the numerator of the argument of the logarithm is the exponential-time-weighted, root-mean-
square, frequency-weighted sound pressure at observation time t.
NOTE 4 The sketch in figure 1 illustrates the process indicated by equation (1).
Low-pass filter with
Square
Square one real pole at –1/W Logarithm
root
Result in decibels
Frequency
reference p
weighted
input
IEC  1082/02
Figure 1 – Principal steps involved in forming an exponential-time-weighted sound level

61672-1 ” IEC:2002 – 15 –
3.6
maximum time-weighted sound level
greatest time-weighted sound level within a stated time interval
NOTE 1 Maximum time-weighted sound level is expressed in decibels (dB).
NOTE 2 For maximum time-weighted sound level, example letter symbols are L , L , L , and L
AFmax ASmax CFmax CSmax
for frequency weightings A and C and time weightings F and S.
3.7
peak sound pressure
greatest absolute instantaneous sound pressure during a stated time interval
3.8
peak sound level
twenty times the logarithm to the base ten of the ratio of a peak sound pressure to the
reference sound pressure, peak sound pressure being obtained with a standard frequency
weighting
NOTE 1 Peak sound level is expressed in decibels (dB).
NOTE 2 This standard provides specifications for measurement of peak C sound level; symbol L .
Cpeak
3.9
time-average sound level
equivalent continuous sound level
twenty times the logarithm to the base ten of the ratio of a root-mean-square sound pressure
during a stated time interval to the reference sound pressure, sound pressure being obtained
with a standard frequency weighting
NOTE 1 Time-average or equivalent continuous sound level is expressed in decibels (dB).
NOTE 2 In symbols, time-average, A-weighted sound level, L or L , is given by
T T
A Aeq
1/ 2
t
­½
ªº
LL 20 lg 1/T p [[d p (2)
®¾
AATTeq A 0
³
«»tT
¬¼
¯¿
where
– [ is a dummy variable of time integration over the averaging time interval ending at the time of observation t;
– T is the averaging time interval;
– p ([) is the A-weighted instantaneous sound pressure; and
A
– p is the reference sound pressure.
In equation (2), the numerator of the argument of the logarithm is the root-mean-square, frequency-weighted sound
pressure over averaging time interval T.
NOTE 3 In principle, time weighting is not involved in a determination of time-average sound level.
3.10
sound exposure
time integral of the square of sound pressure over a stated time interval or event
NOTE 1 Duration of integration is included implicitly in the time integral and need not be reported explicitly,
although the nature of the event should be stated. For measurements of sound exposure over a specified time
interval such as 1 h, duration of integration should be reported.
NOTE 2 In symbols, A-weighted sound exposure E of a specified event is represented by
A
t
(3)
Ep ()tdt
AA
³
t
61672-1 ” IEC:2002 – 17 –
where p (t) is the square of the A-weighted instantaneous sound pressure during an integration time starting at t
A 1
and ending at t .
The unit of A-weighted sound exposure is pascal-squared seconds if A-weighted sound pressure is in pascals and
running time is in seconds.
NOTE 3 Sound exposure in pascal-squared hours is more convenient for applications such as measurement of
exposure to noise in the workplace; see IEC 61252 [2].
3.11
sound exposure level
ten times the logarithm to the base ten of the ratio of a sound exposure to the reference
sound exposure, reference sound exposure being the product of the square of the reference
sound pressure and the reference time interval of 1 s
NOTE 1 Sound exposure level is expressed in decibels (dB).
NOTE 2 In symbols, A-weighted sound exposure level, L , is related to a corresponding measurement of
E
A
time-average, A-weighted sound level, L or L , by
T T
A Aeq
t
ªº
Lp 10 lg tdtpT 10 lg(E /E ) L 10 lg(T /T ) (4)

AAE 00 A0AT 0
³
^`
«»t
¬¼1
where
– E is the A-weighted sound exposure in pascal-squared seconds (see equation (3));
A
2 -12 2
– E is the reference sound exposure of (20 PPa) u (1 s) = 400 u 10 Pa s;
– T = 1 s; and
– T = t – t is the time interval for measurement, in seconds, for sound exposure level and time-average sound
2 1
level.
NOTE 3 Time-average, A-weighted sound level L or L during time interval T is related to the total
T T
A Aeq
A-weighted sound exposure E occurring within that interval by
A
0,1L
AT
Ep T 10 (5a)
A0
or
ªº
LE 10 lg pTL 10 lgTT (5b)
AATE0 A 0
¬¼
3.12
microphone reference point
point specified on, or close to, the microphone to describe the position of the microphone
NOTE The microphone reference point may be at the centre of the diaphragm of the microphone.
3.13
reference direction
inward direction toward the microphone reference point and specified for determining the
acoustical response, directional response, and frequency weighting of a sound level meter
NOTE The reference direction may be specified with respect to an axis of symmetry.
3.14
sound-incidence angle
angle between the reference direction and a line between the acoustic centre of a sound
source and the microphone reference point
NOTE Sound-incidence angle is expressed in degrees.
3.15
level range
range of nominal sound levels measured with a particular setting of the controls of a sound
level meter
NOTE Level range is expressed in decibels (dB).

61672-1 © IEC:2002 – 19 –
3.16
reference sound pressure level
sound pressure level specified for testing the electroacoustical performance of a sound level
meter
NOTE Reference sound pressure level is expressed in decibels (dB).
3.17
reference level range
level range specified for testing the electroacoustical characteristics of a sound level meter
and containing the reference sound pressure level
NOTE Reference level range is expressed in decibels (dB).
3.18
calibration check frequency
nominal frequency, in the range from 160 Hz to 1 250 Hz, of the sinusoidal sound pressure
produced by a sound calibrator that is used in checking and adjusting a sound level meter
3.19
level linearity error
at a stated frequency, an indicated signal level minus the anticipated signal level
NOTE Level linearity error is expressed in decibels (dB).
3.20
linear operating range
on any level range and at a stated frequency, the range of sound levels over which level
linearity errors are within the tolerance limits specified in this standard
NOTE Linear operating range is expressed in decibels (dB).
3.21
total range
range of A-weighted sound levels, in response to sinusoidal signals, from the smallest sound
level, on the most-sensitive level range, to the highest sound level, on the least-sensitive level
range, that can be measured without indication of overload or under-range and within the
tolerance limits specified in this standard for level linearity error
NOTE Total range is expressed in decibels (dB).
3.22
toneburst
one or more complete cycles of a sinusoidal signal starting and stopping at a zero crossing of
the waveform
3.23
toneburst response
maximum time-weighted sound level, time-average sound level, or sound exposure level,
measured in response to a sinusoidal electrical toneburst minus the corresponding measured
sound level of the steady sinusoidal input signal from which the toneburst was extracted
NOTE Toneburst response is expressed in decibels (dB).

61672-1 © IEC:2002 – 21 –
3.24
reference orientation
orientation of a sound level meter for tests to demonstrate conformance to the specifications
of this standard for emissions of, and susceptibility to, radio frequency fields
4 Reference environmental conditions
Reference environmental conditions for specifying the performance of a sound level meter
are:
– air temperature 23 °C;
– static pressure 101,325 kPa;
– relative humidity 50 %.
5 Performance specifications
5.1 General
5.1.1 Generally, a sound level meter is a combination of a microphone, a signal processor,
and a display device.
The signal processor includes the combined functions of an amplifier with a specified and
controlled frequency response, a device to form the square of the frequency-weighted time-
varying sound pressure, and a time integrator or time averager. Signal processing that is
necessary to conform to the specifications of this standard is an integral part of a sound level
meter.
In this standard, a display device provides either a physical and visible display, or storage, of
measurement results. Any stored measurement result shall be available for display by means
of a manufacturer-specified device, for instance a computer with associated software.
5.1.2 The performance specifications of this clause apply under the reference environmental
conditions of clause 4.
5.1.3 For specifying the emission of, and susceptibility to, radio frequency fields, sound level
meters are classified into three groups as follows:
− group X sound level meters: self-contained instruments that include sound level
measurement facilities according to this standard and which specify internal battery power
for the normal mode of operation, requiring no external connections to other apparatus to
measure sound levels;
− group Y sound level meters: self-contained instruments that include sound level
measurement facilities according to this standard and which specify connection to a public
supply of electric power for the normal mode of operation, requiring no external
connections to other apparatus to measure sound levels; and
− group Z sound level meters: instruments that include sound level measurement facilities
according to this standard and which require two or more items of equipment, which are
essential constituent parts of the sound level meter, to be connected together by some
means for the normal mode of operation. The separate items may be operated from
internal batteries or from a public supply of electric power.

61672-1 © IEC:2002 – 23 –
5.1.4 The configuration of the complete sound level meter and its normal mode of operation
shall be stated in the instruction manual. If appropriate, the configuration of the complete
sound level meter includes a windscreen and other devices that are installed around the
microphone as integral components for the normal mode of operation.
5.1.5 A sound level meter that is stated in the instruction manual to be a class 1 or class 2
sound level meter shall conform to all mandatory class 1 or class 2 specifications,
respectively, that are provided in this standard. A class 2 sound level meter may provide
some class 1 capabilities, but if any capability conforms only to the class 2 specifications, the
instrument is a class 2 sound level meter. A sound level meter may be specified as a class 1
instrument in one configuration and a class 2 instrument in another configuration (for
example, with a different microphone or preamplifier).
5.1.6 The instruction manual shall state the models of microphones with which the complete
sound level meter conforms to the specifications for class 1 or class 2 performance for sound
waves incident on the microphone from the reference direction in a free field, or with random
incidence, or both, as appropriate. The instruction manual shall describe appropriate
procedures for use of the sound level meter.
5.1.7 The instruction manual shall state how the microphone is to be mounted, if applicable,
to conform to the specifications for directional response and frequency weightings. A
microphone extension device or cable may be required to conform to the specifications. In this
event, the sound level meter shall be stated in the instruction manual as conforming to the
applicable specifications for directional response and frequency weighting only when the
specified devices are installed.
5.1.8 Computer software may be an integral part of the sound level meter. The instruction
manual shall provide unique identification for all such software.
5.1.9 As a minimum, a conventional sound level meter shall provide a means to indicate
A-frequency-weighted and F-time-weighted sound level. As a minimum, an
integrating-averaging sound level meter shall provide a means to indicate A-weighted
time-average sound level. As a minimum, an integrating sound level meter shall provide a
means to indicate A-weighted sound exposure level. Sound level meters may contain any or
all of the design features for which performance specifications are given in this standard. A
sound level meter shall conform to the applicable performance specifications for those design
features that are provided.
5.1.10 A sound level meter shall have frequency-weighting A. Sound level meters
conforming to class 1 tolerance limits also shall have frequency weighting C, at least for
pattern evaluation tests. Sound level meters that measure peak C sound levels for non-steady
sounds shall also measure C-weighted sound levels for steady sounds, at least for pattern
evaluation tests. The ZERO frequency weighting (Z-weighting) is optional. The instruction
manual shall describe all frequency weightings that are provided.
5.1.11 A sound level meter may have more than one display device.
NOTE An a.c., d.c., or digital output connection alone is not a display device.

61672-1 © IEC:2002 – 25 –
5.1.12 A sound level meter may have more than one level range with a suitable level range
control. The instruction manual shall describe the level range(s) by the nominal A-weighted
sound level at 1 kHz. The instruction manual shall describe the operation of the level range
controls and provide recommendations for selecting the optimum level range to display the
results of a measurement of sound level or sound exposure level.
5.1.13 The reference sound pressure level, reference level range, and reference orientation
shall be stated in the instruction manual. The instruction manual shall state the reference
direction for each model of microphone intended for use with the sound level meter; the
position of the microphone reference point shall also be stated.
NOTE A reference sound pressure level of 94 dB is preferred. Alternatively, a reference sound pressure level of
74 dB, 84 dB, 104 dB, 114 dB, or 124 dB may be specified. A sound pressure level of 94 dB corresponds closely to
a root-mean-square sound pressure of 1 Pa.
5.1.14 A hold feature shall be provided, for measurements of maximum time-weighted sound
level and peak C sound level if the sound level meter is capable of measuring these
quantities. The instruction manual shall describe the operation of the hold facility and the
means for clearing a display that is held.
5.1.15 Determination of conformance to many specifications of this standard requires the
application of electrical signals. The electrical signals are to be equivalent to signals from the
microphone. As appropriate for each specified model of microphone, the design goal and
applicable tolerance limits shall be stated in the instruction manual for the electrical
characteristics of the device, or the means, to insert signals into the electrical input facility.
Electrical characteristics include the resistive and reactive components of the electrical
impedance at the output of the device. The design goal for the impedance shall be specified
for a frequency of 1 kHz.
5.1.16 The instruction manual shall state the highest sound pressure level at the microphone
and the greatest peak-to-peak voltage that can be applied at the electrical input facility
without causing damage to the sound level meter.
5.1.17 Performance specifications in this standard apply, as appropriate, to any time or
frequency weightings operated in parallel and to each independent channel of a multi-channel
sound level meter. The instruction manual shall describe the characteristics and operation of
each independent channel.
NOTE A multi-channel sound level meter may have two or more microphone inputs.
5.1.18 Specifications for the electroacoustical response of a sound level meter apply after
an initial time interval following switching on the power. The initial time interval, stated in the
instruction manual, shall not exceed 2 min. The sound level meter shall be allowed to reach
equilibrium with the prevailing ambient environment before switching on the power.
5.1.19 Tolerance limits in this standard include allowances for design and manufacturing and
for the maximum expanded uncertainties of measurement for the tests to demonstrate
conformance to the specifications (see annex A).
NOTE In some cases, the tolerance limits in this standard are larger than the tolerance limits for corresponding
characteristics in IEC 60651 and IEC 60804. Tolerance limits in IEC 60651 [3] and in IEC 60804 [4] did not include
allowances for uncertainties of measurement.

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5.2 Adjustments to indicated levels
5.2.1 At least one model of sound calibrator shall be stated in the instruction manual for
checking and maintaining the correct indication on the display of the sound level meter.
5.2.2 For class 1 sound level meters, the sound calibrator shall conform to the class 1
specifications of IEC 60942. For class 2 sound level meters, the sound calibrator shall
conform to either the class 1 or the class 2 specifications of IEC 60942.
NOTE Laboratory standard sound calibrators are not suitable for general applications with sound level meters
because their performance characteristics are specified in IEC 60942 only for a limited range of environmental
conditions.
5.2.3 For the reference sound pressure level on the reference level range and for the
calibration check frequency, a procedure and data shall be provided in the instruction manual
to adjust the sound level displayed in response to application of the sound calibrator specified
in 5.2.1 and 5.2.2. Application of the procedure and the adjustment data shall yield the sound
level or sound exposure level that would be indicated in response to plane progressive
sinusoidal sound waves incident from the reference direction or in response to sounds at
random incidence, as appropriate.
The procedure and data shall apply for environmental conditions at least within the applicable
ranges specified in clause 6, including the reference environmental conditions. The
adjustment data shall apply to microphones of all models stated in the instruction manual for
use on the sound level meter and to any associated devices provided by the manufacturer of
the sound level meter for mounting a microphone on the instrument. The data shall include
corrections for the average effects of a windscreen on microphone frequency response if a
windscreen is an integral component of the sound level meter for the normal mode of
operation or if the instruction manual states that the sound level meter conforms to the
specifications of this standard with a recommended windscreen installed around the micro-
phone.
5.2.4 For microphones of all models that are stated in the instruction manual to be for use
on the sound level meter, the instruction manual shall provide data for corrections for the
deviation of the average microphone frequency response from a uniform frequency response,
and for the average effects of reflections from the case of the sound level meter and
diffraction around the microphone. The average effects of reflections and diffraction are
relative to the sound pressure level at the position of the microphone and in the absence of
the sound level meter.
If the instruction manual states that the sound level meter conforms to the specifications of
this standard both with and without a windscreen installed around the microphone, the data
described above shall be given for both configurations. The data for the configuration with
windscreen shall include the corrections for the average effects of a windscreen on
microphone frequency response. If a windscreen is an integral component of the sound level
meter for the normal mode of operation, the windscreen correction data shall be given only for
this configuration.
The corrections for the average frequency response of a microphone and for the average
effects of reflections, diffraction, and windscreen, if applicable, shall apply for plane
progressive sinusoidal sound waves incident from the reference direction and in the absence
of wind. The information shall include the associated values for expanded uncertainties of
measurement. The expanded uncertainties of measurement and the basic information shall be
given in tabular form separately in the instruction manual.
NOTE The corrections for the average frequency response of the microphone and for the average effects of
reflections and diffraction may be provided as two separate corrections or as a single combined correction.

61672-1 © IEC:2002 – 29 –
5.2.5 The data required by 5.2.4 shall be provided in the following formats.
− For class 1 sound level meters, the data shall be stated in tabular form at nominal one-
third-octave intervals for frequencies from 63 Hz to 1 kHz and then at nominal one-twelfth-
octave intervals for frequencies greater than 1 kHz to at least 16 kHz.
− For class 2 sound level meters, the data shall be stated in tabular form at nominal one-
third-octave intervals for frequencies from 63 Hz to at least 8 kHz.
− Corrections for the average effects of a windscreen on the microphone frequency
response shall be stated in tabular form at nominal one-third-octave intervals from 1 kHz
to 16 kHz for class 1 sound level meters and from 1 kHz to 8 kHz for class 2 sound level
meters.
5.2.6 Deviations of the measured effects of microphone frequency response, reflection,
diffraction, and windscreen, if applicable, from the effects stated in the instruction manual,
extended by the expanded uncertainty of measurement, shall not exceed two thirds of the
applicable tolerance limits in table 2.
5.2.7 If the instruction manual recommends a sound calibrator or an electrostatic actuator
for use during periodic testing, the instruction manual shall provide adjustment data to obtain
equivalent A-weighted sound levels that would be displayed under reference environmental
conditions in response to plane progressive sinusoidal sound waves incident from the
reference direction. These adjustment data shall apply to the A-weighted sound levels
displayed in response to the sound pressure produced by a calibrated multi-frequency sound
calibrator or in response to simulation of sound pressure by an electrostatic actuator.
5.2.8 The adjustment data shall be provided at least for frequencies of 125 Hz, 1 kHz, and
either 4 kHz or 8 kHz and shall apply for stated combinations of a microphone, sound level
meter, and a model of sound calibrator or electrostatic actuator. The adjustment data shall be
provided for all models of microphones or microphone-wi
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