IEC 60942:2017

IEC 60942 ®
Edition 4.0 2017-11
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Electroacoustics – Sound calibrators

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IEC 60942 ®
Edition 4.0 2017-11
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Electroacoustics – Sound calibrators

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.140.50; 33.100.20 ISBN 978-2-8322-5135-5

– 2 – IEC 60942:2017 RLV © IEC 2017
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 10
4 Reference environmental conditions . 12
5 Requirements . 12
5.1 General . 12
5.2 Adaptors . 16
5.3 Sound pressure level . 16
5.3.1 General . 16
5.3.2 Generated sound pressure level . 16
5.3.3 Short-term level fluctuation . 16
5.3.4 Sound pressure level over range of supply voltage . 17
5.4 Frequency . 18
5.4.1 General . 18
5.4.2 Frequency of sound generated by the sound calibrator . 18
5.5 Influence of static pressure, air temperature and humidity . 18
5.6 Total distortion + noise . 20
5.7 Power supply requirements . 21
5.8 Specification and calibration of microphones . 21
5.8.1 Microphone models and adaptors . 21
5.8.2 Microphone sensitivity level . 21
5.9 Electromagnetic compatibility . 22
5.9.1 General . 22
5.9.2 Radio-frequency emissions . 22
5.9.3 Electrostatic discharges . 22
5.9.4 Immunity to power- and radio-frequency fields . 22
6 Instrument marking and documentation . 23
6.1 Marking of the sound calibrator . 23
6.2 Individual calibration chart for a class LS sound calibrator . 24
6.3 Instruction manual . 24
Annex A (normative) Pattern evaluation tests . 26
A.1 Introduction General . 26
A.2 Submission for test . 27
A.3 Principal values . 27
A.4 Marking of the sound calibrator and supplied documentation . 27
A.5 Performance tests at and around reference environmental conditions . 27
A.5.1 General . 27
A.5.2 Orientation . 28
A.5.3 Ambient noise . 28
A.5.4 Microphone specification . 28
A.5.5 Sound pressure level . 28
A.5.6 Sound pressure level stability – Short-term level fluctuation . 30
A.5.7 Frequency . 31

A.5.8 Total distortion + noise . 32
A.6 Environmental tests . 33
A.6.1 General . 33
A.6.2 Influence of static pressure . 34
A.6.3 Acclimatization requirements for tests of the influence of variations in
air temperature and relative humidity . 35
A.6.4 Abbreviated test of influence of air temperature and humidity combined . 35
A.6.5 Influence of air temperature . 38
A.6.6 Influence of relative humidity . 39
A.6.7 Influence of air temperature and humidity combined . 40
A.7 Electromagnetic compatibility . 41
A.7.1 General . 41
A.7.2 Radio-frequency emissions . 42
A.7.3 Electrostatic discharges . 42
A.7.4 Immunity to power- and radio-frequency fields . 43
Annex B (normative) Periodic tests . 45
B.1 Introduction General . 45
B.2 Submission for test . 46
B.3 Preliminary inspection . 46
B.4 Performance tests . 46
B.4.1 Orientation . 46
B.4.2 Ambient noise . 46
B.4.3 Environmental conditions . 46
B.4.4 Additional equipment . 47
B.4.5 Microphone specification . 47
B.4.6 Sound pressure level . 47
B.4.7 Frequency . 49
B.4.8 Total distortion + noise . 49
B.5 Calibration of the sound calibrator with other models of microphone . 50
B.6 Documentation . 50
Annex C (normative) Format for the Pattern evaluation report . 52
C.1  Introduction General . 52
C.2 Marking . 52
C.3 Submission for test . 52
C.4 Pattern evaluation report content . 52
Annex D (informative) Relationship between tolerance interval, corresponding
acceptance interval and the maximum-permitted uncertainty of measurement . 93
Annex E (informative) Example assessments of conformance to specifications of this
document . 94
E.1 General . 94
E.2 Conformance criteria . 94
E.3 Example test results . 94
Bibliography . 97

Figure D.1 – Relationship between tolerance interval, corresponding acceptance
interval and the maximum-permitted uncertainty of measurement . 93
Figure E.1 – Examples of assessment of conformance . 96

– 4 – IEC 60942:2017 RLV © IEC 2017
Table 1 – Sound calibrator classes and designations . 14
Table 2 – Tolerance Acceptance limits for sound pressure level and short-term level
fluctuation, at and around reference environmental conditions . 17
Table 3 – Tolerance Acceptance limits for the effect of supply voltage on sound
pressure level, under reference environmental conditions . 18
Table 4 – Tolerance Acceptance limits for frequency, at and around reference
environmental conditions . 18
Table 5 – Tolerance Acceptance limits for sound pressure level, over the specified
range of environmental conditions . 20
Table 6 – Tolerance Acceptance limits for frequency, over the specified range of
environmental conditions . 20
Table 7 – Maximum total distortion + noise . 21
Table A.1 – Maximum-permitted expanded uncertainty of measurement for a coverage
probability of 95 %, for sound pressure level and short-term level fluctuation at and
around reference environmental conditions . 31
Table A.2 – Maximum-permitted expanded uncertainty of measurement for a coverage
probability of 95 % for frequency, at and around reference environmental conditions . 32
Table A.3 – Maximum-permitted expanded uncertainty of measurement for a coverage
probability of 95 % for total distortion + noise, over the appropriate range of
environmental conditions . 33
Table A.4 – Maximum-permitted expanded uncertainty of measurement for a coverage
probability of 95 %, for sound pressure level, over the specified range of environmental
conditions . 35
Table A.5 – Maximum-permitted expanded uncertainty of measurement for a coverage
probability of 95 % for frequency, over the specified range of environmental conditions . 38
Table E.1 – Examples of assessment of conformance . 95

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROACOUSTICS – SOUND CALIBRATORS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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This redline version of the official IEC Standard allows the user to identify the changes
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– 6 – IEC 60942:2017 RLV © IEC 2017
International Standard IEC 60942 has been prepared by IEC technical committee 29:
Electroacoustics, in cooperation with the International Organization of Legal Metrology
(OIML).
This fourth edition cancels and replaces the third edition published in 2003, of which it
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) deletion of the class designations, class LS/C, class 1/C and class 2/C;
b) addition of two further class designations, class LS/M and class 1/M, specifically for
pistonphones;
c) addition of an amended criterion for assessing conformance to a specification:
conformance is now demonstrated when (a) measured deviations from design goals do not
exceed the applicable acceptance limits and (b) the uncertainty of measurement does not
exceed the corresponding maximum-permitted uncertainty;
d) modification to the short-term level fluctuation test of the sound pressure level stability;
e) change to some environmental test conditions to avoid icing;
f) addition of an alternative test for immunity to radio-frequency fields using transverse
electromagnetic (TEM) waveguides.
The text of this International Standard is based on the following documents:
FDIS Report on voting
29/962/FDIS 29/969/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

INTRODUCTION
Sound calibrators are designed to produce one or more known sound pressure levels at one
or more specified frequencies when coupled to specified models of microphone in specified
configurations, for example, with or without protective grid. The sound pressure level
generated by a some sound calibrators may depends on environmental conditions such as the
static pressure, air temperature and relative humidity.
Sound calibrators have two principal applications:
a) the determination of the electroacoustical pressure sensitivity of specified models of
microphone in specified configurations;
b) checking or adjusting the overall sensitivity of acoustical measuring devices or systems.

– 8 – IEC 60942:2017 RLV © IEC 2017
ELECTROACOUSTICS – SOUND CALIBRATORS

1 Scope
This document specifies the performance requirements for three classes of sound calibrator:
class LS (Laboratory Standard), class 1 and class 2. Tolerance Acceptance limits are smallest
for class LS and greatest for class 2 instruments. Class LS sound calibrators are normally
used only in the laboratory; class 1 and class 2 are considered as sound calibrators for field
use. A class 1 sound calibrator is primarily intended for use with a class 1 sound level meter
and a class 2 sound calibrator primarily with a class 2 sound level meter, as specified in
IEC 61672-1.
The tolerance acceptance limits for class LS sound calibrators are based on the use of a
laboratory standard microphone, as specified in IEC 61094-1, for demonstrations of
conformance to the requirements of this document. The tolerance acceptance limits for
class 1 and class 2 sound calibrators are based on the use of a working standard microphone,
as specified in IEC 61094-4, for demonstrations of conformance to the requirements of this
document.
A multi-level and multi-frequency sound calibrator has the same class designation for all
sound pressure level and frequency combinations for which the instruction manual states that
the instrument conforms to the requirements of this standard.
To promote consistency of testing of sound calibrators and ease of use, this document
contains three normative annexes – Annex A "Pattern evaluation tests", Annex B "Periodic
tests", Annex C "Pattern evaluation report", and two informative Annexes – Annex D
"Relationship between tolerance interval, corresponding acceptance interval and the
maximum-permitted uncertainty of measurement" and Annex E "Example assessments of
conformance to specifications of this document".
This document does not include requirements for equivalent free-field or random-incidence
sound pressure levels, such as may can be used in the overall sensitivity adjustment of a
sound level meter.
A sound calibrator may can provide other functions, for example, tonebursts. Requirements
for these other functions are not included in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050-801:1994, International Electrotechnical Vocabulary – Chapter 801: Acoustics and
electroacoustics
IEC 61000-4-2:1995 2008, Electromagnetic compatibility (EMC) – Part 4-2: Testing and
measurement techniques – Electrostatic discharge immunity test. Basic EMC Publication
IEC 61000-4-3:2002 2006, Electromagnetic compatibility (EMC) – Part 4-3: Testing and
measurement techniques – Radiated, radio-frequency, electromagnetic field immunity test
Basic EMC Publication
IEC 61000-4-20:2010, Electromagnetic compatibility (EMC) – Part 4-20: Testing and
measurement techniques – Emission and immunity testing in transverse electromagnetic
(TEM) waveguides
IEC 61000-6-1:1997 2005, Electromagnetic compatibility (EMC) – Part 6-1: Generic standards
– Immunity for residential, commercial and light-industrial environments
IEC 61000-6-2:2005, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61000-6-3:2006, Electromagnetic compatibility (EMC) – Part 6-3: Generic standards –
Emission standard for residential, commercial and light-industrial environment
IEC 61000-6-3:2006/AMD1:2010
IEC 61094-1:2000, Measurement microphones – Part 1: Specifications for laboratory standard
microphones
IEC 61094-2:1992, Measurement microphones – Part 2: Primary method for pressure
calibration of laboratory standard microphones by the reciprocity technique
IEC 61094-4:1995, Measurement microphones – Part 4: Specifications for working standard
microphones
IEC 61094-5:2001, Electroacoustics – Measurement microphones – Part 5: Methods for
pressure calibration of working standard microphones by comparison
IEC 61672-1:2002, Electroacoustics – Sound level meters – Part 1: Specifications
CISPR 16-1-1, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring
apparatus
CISPR 16-2-3:2016, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 2-3: Methods of measurement of disturbances and immunity – Radiated
disturbance measurements
CISPR 22:1997 2008, Information technology equipment – Radio disturbance characteristics –
Limits and methods of measurement
CISPR/IEC 61000-6-3:1996, Electromagnetic compatibility (EMC) – Part 6: Generic standards –
Section 3: Emission standard for residential, commercial and light-industrial environments
ISO/IEC Guide:1995, Guide to the expression of uncertainty in measurement
___________
nd nd rd
2 edition (2005). This 2 edition has been replaced in 2016 by a 3 edition IEC 61000-6-1:2016,
Electromagnetic compatibility (EMC) – Part 6-1: Generic standards – Immunity standard for residential,
rd
commercial and light-industrial environments, but to ensure consistency with other TC 29 standards this 3
edition has not been used or referenced in this document, but will be considered prior to the next revision of
this document.
nd nd rd
2 edition (2005). This 2 edition has been replaced in 2016 by a 3 edition IEC 61000-6-2:2016,
Electromagnetic compatibility (EMC) – Part 6-2: Generic standards – Immunity for industrial environments, but
rd
to ensure consistency with other TC 29 standards this 3 edition has not been used or referenced in this
document, but will be considered prior to the next revision of this document.
th th
6 edition (2008). This 6 edition has been replaced in 2015 by CISPR 32:2015, Electromagnetic compatibility
of multimedia equipment – Emission requirements, but to ensure consistency with other TC 29 standards
CISPR 32:2015 has not been used or referenced in this document, but will be considered prior to the next
revision of this document.
– 10 – IEC 60942:2017 RLV © IEC 2017
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
ISO 266:1997, Acoustics – Preferred frequencies
ISO/IEC Guide 99, International vocabulary of metrology – Basic and general concepts and
associated terms (VIM)
ISO Publication:1993, ISBN 92-67-01075-1, International vocabulary of Basic and general
terms in metrology
OIML International Recommendation R 97:1990, Barometers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-801 and the
ISO Publication International Vocabulary of Basic and General Terms in Metrology ISO/IEC
Guide 99, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE Definitions for other relevant quantities are given in the documents referenced in Clause 2.
3.1
sound calibrator
device that generates a sinusoidal sound pressure of specified sound pressure level and
frequency when coupled to specified models of microphone in specified configurations
3.2
pistonphone
sound calibrator in which the sound pressure is generated in a fixed air volume by the motion
of one or more pistons, creating a well-defined volume velocity
3.3
specified sound pressure level
sound pressure level(s) generated under reference environmental conditions for use with a
particular microphone model and configuration, valid for either an individual sound calibrator
(in the case of a class LS calibrator) or all sound calibrators of the same model (in the case of
a class 1 or class 2 calibrator)
Note 1 to entry: Specified sound pressure level is expressed in decibels (dB).
Note 2 to entry: The reference value is 20 µPa.
3.4
nominal sound pressure level
close approximation to the specified sound pressure level(s), valid for all sound calibrators of
the same model, rounded to the nearest decibel (intended for marking)
Note 1 to entry: Nominal sound pressure level is expressed in decibels (dB).
Note 2 to entry: The reference value is 20 µPa.

3.5
specified frequency
frequency(ies) of the sound generated by the sound calibrator under reference environmental
conditions, valid for either an individual sound calibrator (in the case of a class LS calibrator)
or all sound calibrators of the same model (in the case of a class 1 or class 2 calibrator)
Note 1 to entry: Specified frequency is expressed in hertz (Hz).
3.6
nominal frequency
close approximation to the specified frequency, often rounded according to ISO 266 (intended
for marking)
Note 1 to entry: Nominal frequency is expressed in hertz (Hz).
3.7
principal sound pressure level
nominal sound pressure level specified in the instruction manual as principal
Note 1 to entry: Where the sound calibrator produces more than one sound pressure level, the manufacturer
identifies one nominal sound pressure level as principal.
Note 2 to entry: Principal sound pressure level is used during demonstration of conformance of the sound
calibrator to the requirements of this document.
Note 3 to entry: Principal sound pressure level is expressed in decibels (dB).
Note 4 to entry: The reference value is 20 µPa.
3.8
principal frequency
nominal frequency specified in the instruction manual as principal
Note 1 to entry: Where the sound calibrator produces more than one frequency, the manufacturer identifies one
nominal frequency as principal.
Note 2 to entry: Principal frequency is used during demonstration of conformance of the sound calibrator to the
requirements of this document.
Note 3 to entry: Principal frequency is expressed in hertz (Hz).
3.9
replication
repeat of a measurement involving coupling the microphone to the sound calibrator and then
completely removing the microphone from the sound calibrator
3.10
total distortion + noise
ratio of the root-mean-square of the total distortion and noise components, including any
harmonics and sub-harmonics, to the root-mean-square of the entire signal
Note 1 to entry: Distortion is the correlated component of the signal due to non-linearity, and noise is the
uncorrelated component.
Note 2 to entry: Total distortion + noise is expressed in per cent (%).
3.11
reference orientation
orientation of a sound calibrator such that the principal axis of the opening of the cavity (the
axis along which the microphone is inserted into the cavity) coincides with the principal
direction of an emitter or receiver of radio-frequency fields, the opening of the cavity facing
away from the emitter or receiver

– 12 – IEC 60942:2017 RLV © IEC 2017
3.12
reference plane
plane of contact between the microphone and the sound calibrator
3.13
effective load volume of a microphone
volume of air at reference environmental conditions that has the same acoustic compliance as
the cavity bounded by the reference plane, the microphone diaphragm and the outer
cylindrical surface of the microphone at the reference plane, including the equivalent volume
of the microphone (described in IEC 61094-1)
Note 1 to entry: Effective load volume is generally expressed in cubic millimetres (mm ) and may change with
frequency.
3.14
coverage probability
probability that the set of true quantity values of a measurand is contained within a specified
coverage interval
[SOURCE: ISO/IEC Guide 98-4:2012, 3.2.8]
3.15
acceptance limit
specified upper or lower bound of permissible measured quantity values
Note 1 to entry: Acceptance limits in this document are analogous to the allowances for design and manufacturing
in IEC 60942:2003.
[SOURCE: ISO/IEC Guide 98-4:2012, 3.3.8, modified – Note 1 to entry has been added.]
4 Reference environmental conditions
Reference environmental conditions for specifying the performance of a sound calibrator are:
– air temperature: 23 °C;
– static pressure: 101,325 kPa;
– relative humidity: 50 %.
5 Requirements
5.1 General
5.1.1 A sound calibrator conforming to the requirements of this document shall have the
characteristics described in Clause 5. Adaptors may be provided to accommodate more than
one model of microphone. For the purpose of this document, any such adaptor is an integral
part of the sound calibrator.
5.1.2 The sound calibrator shall conform to the requirements of this document for one or
more of the sound pressure level and frequency combinations available. All the combinations
conforming to the requirements given in this standard shall conform to the same class
designation. A multi-level and multi-frequency sound calibrator shall conform to the
requirements for the same class designation for all sound pressure level and frequency
combinations for which the instruction manual states that the instrument conforms to the
requirements of this document. Conformance to the requirements of this document shall not
be stated for sound pressure level and frequency settings for which this document provides no
tolerance acceptance limits.
5.1.3 Throughout this document, where reference is made to a specific class of sound
calibrator, this includes all the designations under that class, unless otherwise stated.
5.1.4 Class LS sound calibrators shall be supplied with an individual calibration chart
containing the information required by 6.2. For class 1 and class 2 sound calibrators, the
specified sound pressure level(s) and specified frequency(ies) shall be given in the instruction
manual. Each specified level shall be defined in terms of an absolute level.
5.1.5 Class LS and class 1 sound calibrators pistonphones that require corrections for the
influence of static pressure to conform to the specifications for the appropriate class shall
have the letter "C M" added to their class designation. Class LS and class 1 sound calibrators
shall not require corrections for any of the other environmental conditions to achieve the
requirements specified for the appropriate class. Class 2 sound calibrators that require
corrections for any of the environmental conditions to conform to the specified requirements
shall have the letter ‘C’ added to their class designation. Where appropriate, the class
designation shall be described as class LS/C, class 1/C, class 2/C. Where corrections are
permitted, and are necessary to conform to the specified requirements as an environmental
condition varies, these corrections shall be stated in the instruction manual. The permissible
classes and designations are described in Table 1. Sound calibrators designated class LS/M
and class 1/M shall not require corrections for any of the other environmental conditions to
achieve the requirements specified for the appropriate class. For class LS/M and class 1/M
sound calibrators, the corrections for static pressure, necessary for the sound calibrator to
conform to the requirements of this document, shall be stated in the instruction manual,
together with the uncertainties of measurement corresponding to a coverage probability of
95 %.
5.1.5 Class 1 sound calibrators that require a correction for the influence of static pressure
to conform to the specifications of this standard shall be supplied with a barometer. The
barometer shall enable the static pressure to be measured so that the ability of a sound
calibrator to conform to the requirements for the class is not affected. Class 2 sound
calibrators that require a correction for the influence of static pressure to conform to the
specifications of this standard shall be supplied with a barometer (which shall enable the
static pressure to be measured in such a way that the ability of a sound calibrator to conform
to the requirements for the class is not affected), unless the corrections are sufficiently small
that for any change in static pressure of ±6,0 kPa the uncorrected measured sound pressure
levels conform to the specifications of this standard. In this case, the corrections to be applied
for the influence of variations in static pressure shall be stated in the instruction manual,
together with information on how to calculate the relevant correction when operating the
sound calibrator at different heights above sea-level.
NOTE 1 A class LS sound calibrator is normally used only in the laboratory where a suitable device should be
available for measuring static pressure if the sound calibrator has a class ‘C’ designation. Hence, there is no
requirement to supply a barometer for this class.
NOTE 2 The barometer may provide the data directly in the form to be used to correct measured sound pressure
levels to the reference static pressure.
5.1.6 Where a class 2 sound calibrator, that requires a correction for the influence of
temperature or relative humidity to conform to the specifications of this standard, is supplied
with the means to measure the relevant environmental condition, the supplied means shall
enable the condition to be measured in such a way that the ability of a sound calibrator to
conform to the requirements for the class is not affected.
NOTE The ‘supplied means’ may provide the data directly in the form to be used to correct
measured sound pressure levels to the reference environmental conditions.
5.1.7 The design of the sound calibrator and the materials used in the construction should
be such as to provide long-term stability for the operation of the sound calibrator.

– 14 – IEC 60942:2017 RLV © IEC 2017
5.1.6 Sound calibrators designated class LS/M may also claim conformance to the
requirements for a sound calibrator designated class 1/M if they meet the full specifications
described in this document for both classes of sound calibrator.
5.1.7 Sound calibrators, other than those designated class LS/M or class 1/M, shall not
require corrections for any of the environmental conditions to conform to the requirements for
the relevant class.
5.1.8 Sound calibrators designated class LS/M and class1/M shall either be supplied with a
barometer, or the manufacturer shall state the specifications in the instruction manual for any
barometer to be used. A statement shall be included in the instruction manual giving the
uncertainty of the measurement of static pressure required, for a coverage probability of 95%,
so that the ability of a class LS/M or class 1/M sound calibrator to conform to the
requirements for the relevant class is not affected.
NOTE 1 A class LS/M sound calibrator is normally used only in the laboratory where a suitable device is likely to
be available for measuring static pressure.
NOTE 2 Some barometers provide the data directly in the form to be used to correct measured sound pressure
levels to the reference static pressure.
Table 1 – Sound calibrator classes and designations
Class Designation Description
Sound calibrator designed to meet the
specifications of this document for a class LS
LS
device with no corrections for the influence of
environmental conditions
LS
Pistonphone designed to meet the specifications of
this document for a class LS device with the
LS/M
application of corrections for the influence of static
pressure only
Sound calibrator designed to meet the
specifications of this document for a class 1 device
with no corrections for the influence of
environmental conditions
Pistonphone designed to meet the specifications of
this document for a class 1 device with the
1/M
application of corrections for the influence of static
pressure only
Sound calibrator designed to meet the
specifications of this document for a class 2 device
2 2
with no corrections for the influence of
environmental conditions
5.1.9 If a specific orientation of the sound calibrator is to be used to conform to the
requirements of this document, this orientation shall either be indicated on the sound
calibrator, or the indication on the sound calibrator shall refer to the instruction manual, which
shall state the required orientation.
5.1.10 All performance requirements relate to the operation of the sound calibrator following
stabilizing of the coupling of the microphone and sound calibrato
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