SIST EN 60068-2-65:2013

Environmental testing - Part 2-65: Tests - Test Fg: Vibration - Acoustically induced method

This part of IEC 60068 provides standard procedures and guidance for conducting acoustic tests in order to determine the ability of a specimen to withstand vibration caused by a specified sound-pressure level environment to which it is, or is liable to be, subjected. For sound pressure level environments of less than 120 dB acoustic tests are not normally required. This standard determines the mechanical weakness and/or degradation in the performance of specimens and to use this information, in conjunction with the relevant specification, to decide on their acceptability for use. The methods of test may also be used as a means of establishing the mechanical robustness or fatigue resistance of specimens.
Two procedures are described for conducting tests and for measurement of the sound pressure levels within the acoustic noise field and considers the need for measurement of the vibration responses at specified points on the specimen. It also gives guidance for the selection of the acoustic noise environment, spectrum, sound pressure level and duration of exposure. The progressive wave tube method is relevant to material where aerodynamic turbulence will excite part, or all, of the total external surface. Such applications include aircraft panel assemblies where the excitation exists on one side only. The reverberant chamber method is relevant where it is preferable to induce vibration onto the entire external surface of equipment by distributed excitation rather than fixed points by means of electro-dynamic shakers.

Umgebungseinflüsse - Teil 2-65: Prüfverfahren - Prüfung Fg: Schwingen - akustisch angeregt

Essais d’environnement - Partie 2-65: Essais - Essai Fg: Vibrations - Méthode induite acoustiquement

La CEI 60068-2-65:2013 fournit des méthodes normalisées et un guide pour la conduite d'essais acoustiques afin de déterminer l'aptitude d'un spécimen à résister à des vibrations provoquées par un environnement de niveau de pression acoustique spécifié auquel il est, ou est susceptible d'être, exposé. Cette deuxième édition annule et remplace la deuxième édition, publiée en 1993, dont elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:  - des modifications techniques et rédactionnelles mineures ont été faites dans toute la norme, tel qu'il a été demandé à l'origine par le Comité national allemand;  - conformément aux commentaires émis au stade CD, en particulier ceux du Comité national britannique, des ajouts techniques et éditoriaux significatifs ont été réalisés dans la norme pour l'essai acoustique employant le technique du tube à ondes progressives.

Okoljsko preskušanje - 2-65. del: Preskusi - Preskus Fg: Vibracije - Metode, povzročene z zvokom

Ta del IEC 60068 ponuja standardne postopke in smernice za izvajanje akustičnih testov z namenom določanja vzdržljivosti vzorca na vibracije, ki jih povzroči določeno okolje z ravnjo zvočnega tlaka, ki ji je ali mora biti podvrženo. Za okolja z ravnjo zvočnega tlaka, ki je nižja od 120 dB, akustični testi običajno niso potrebni. Ta standard določa mehanične slabosti in/ali zmanjšanje zmogljivosti vzorcev in uporabo teh informacij, v povezavi z ustreznimi specifikacijami, z namenom odločanja o sprejemljivosti njihove uporabe. Testne metode se lahko uporabljajo tudi za določanje mehanske robustnosti ali odpornosti proti utrujanju vzorcev.
Za izvajanje testov in merjenje ravni zvočnega tlaka v polju akustičnega šuma sta opisana dva postopka ob upoštevanju potrebe za merjenje vibracijskega odziva na določeni točki vzorca. Vsebuje tudi izbiro okolja akustičnega šuma, spektra, raven zvočnega tlaka in čas izpostavljenosti. Metoda progresivnega vala v cevi je pomembna za material, kjer aerodinamična turbulenca vzbuja del ali celotno zunanjo površino. Med takšne uporabe sodijo sestavi panelov letal, kjer je vzbujanje prisotno samo na eni strani. Metoda odbijajoče komore je pomembna tam, kjer je bolj priporočljivo sprožiti vibracijo na celotni zunanji površini opreme s porazdeljenim vzbujanjem kot na določeni točki prek elektrodinamičnih stresalnikov.

General Information

• Status: Published
• Publication Date: 21-May-2013
• ICS: 19.040 - Environmental testing
• Technical Committee: I09 - Imaginarni 09
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 09-May-2013
• Due Date: 14-Jul-2013
• Completion Date: 22-May-2013
• Ref Project: EN 60068-2-65:2013 - Environmental testing - Part 2-65: Tests - Test Fg: Vibration - Acoustically induced method

Relations

• Replaces: SIST EN 60068-2-65:2001 - Environmental testing -- Part 2: Methods of test - Test Fg: Vibration, acoustically induced
• Effective Date: 29-Jan-2023
• Replaces: SIST EN 60068-2-65:2001 - Environmental testing -- Part 2: Methods of test - Test Fg: Vibration, acoustically induced
• Effective Date: 31-May-2011
• Revised: SIST EN 60068-2-65:2001 - Environmental testing -- Part 2: Methods of test - Test Fg: Vibration, acoustically induced
• Effective Date: 06-May-2014

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60068-2-65:2013
01-julij-2013
1DGRPHãþD
SIST EN 60068-2-65:2001
2NROMVNRSUHVNXãDQMHGHO3UHVNXVL3UHVNXV)J9LEUDFLMH0HWRGH
SRY]URþHQH]]YRNRP
Environmental testing - Part 2-65: Tests - Test Fg: Vibration - Acoustically induced
method
Umgebungseinflüsse - Teil 2-65: Prüfverfahren - Prüfung Fg: Schwingen - akustisch
angeregt
Essais d’environnement - Partie 2-65: Essais - Essai Fg: Vibrations - Méthode induite
acoustiquement
Ta slovenski standard je istoveten z: EN 60068-2-65:2013
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
SIST EN 60068-2-65:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60068-2-65:2013

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SIST EN 60068-2-65:2013

EUROPEAN STANDARD
EN 60068-2-65

NORME EUROPÉENNE
May 2013
EUROPÄISCHE NORM

ICS 19.040; 29.020 Supersedes EN 60068-2-65:1994


English version


Environmental testing -
Part 2-65: Tests -
Test Fg: Vibration -
Acoustically induced method
(IEC 60068-2-65:2013)


Essais d’environnement -  Umgebungseinflüsse -
Partie 2-65: Essais - Teil 2-65: Prüfverfahren -
Essai Fg: Vibrations - Prüfung Fg: Schwingen -
Méthode induite acoustiquement akustisch angeregt
(CEI 60068-2-65:2013) (IEC 60068-2-65:2013)





This European Standard was approved by CENELEC on 2013-03-13. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

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

Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60068-2-65:2013 E

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SIST EN 60068-2-65:2013
EN 60068-2-65:2013 - 2 -
Foreword
The text of document 104/591/FDIS, future edition 2 of IEC 60068-2-65, prepared by IEC TC 104
"Environmental conditions, classification and methods of test" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN 60068-2-65:2013.
The following dates are fixed:
(dop) 2013-12-13
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2016-03-13
standards conflicting with the

document have to be withdrawn

This document supersedes EN 60068-2-65:1994.
EN 60068-2-65:2013 includes the following significant technical changes with respect to EN 60068-2-
65:1994:
– minor technical and editorial changes were made throughout the document as originally requested by
the DE National Committee;
– following comments at the CD stage, particularly from the UK National Committee, significant technical
and editorial additions were made to the standard for acoustic testing employing the progressive wave
tube technique.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 60068-2-65:2013 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 60068-1 NOTE  Harmonized as EN 60068-1.
ISO 266 NOTE  Harmonized as EN ISO 266.

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SIST EN 60068-2-65:2013
- 3 - EN 60068-2-65:2013
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

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

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


ISO/IEC 17025 2005 General requirements for the competence of EN ISO/IEC 17025 2005
testing and calibration laboratories

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SIST EN 60068-2-65:2013

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SIST EN 60068-2-65:2013



IEC 60068-2-65

®


Edition 2.0 2013-02




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Environmental testing –

Part 2-65: Tests – Test Fg: Vibration – Acoustically induced method




Essais d’environnement –

Partie 2-65: Essais – Essai Fg: Vibrations – Méthode induite acoustiquement
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX V


ICS 19.040; 29.020 ISBN 978-2-83220-641-6



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60068-2-65:2013
– 2 – 60068-2-65 © IEC:2013
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and abbreviations. 7
3.1 Terms and definitions . 7
3.2 Symbols and abbreviations . 11
4 Acoustic environments and requirements for testing . 11
4.1 Acoustic environment for testing . 11
4.1.1 General . 11
4.1.2 Reverberant field . 13
4.1.3 Progressive wave field . 14
4.1.4 Cavity resonance . 14
4.1.5 Standing wave . 14
4.2 Sound sources . 14
4.3 Measuring apparatus . 14
4.3.1 General . 14
4.3.2 Acoustic measurements . 14
4.3.3 Vibration response measurements . 15
4.3.4 Analysis of results . 15
4.4 Requirements for testing . 15
4.4.1 Type of facility . 15
4.4.2 Mounting . 15
4.4.3 Specimen instrumentation . 16
4.4.4 Preparation of test control . 17
5 Recommended severities . 18
6 Preconditioning . 18
7 Initial measurements . 19
8 Testing . 19
8.1 Normal testing . 19
8.2 Accelerated testing . 19
9 Intermediate measurements . 19
10 Recovery . 19
11 Final measurements . 19
12 Information to be given in the relevant specification . 20
13 Information to be given in the test report . 20
Annex A (informative) Guidance for the test requirements. 22
Bibliography . 30

Figure 1 – Third-octave band spectrum for aeronautical applications . 12
Figure 2 – Octave band spectra for fans derived from [4] . 13
Figure 3 – Octave band spectrum for noisy industrial machinery derived from [4] . 13
Figure 4 – Typical locations of microphone checkpoints (1 – 6) on a fictitious surface
around a specimen . 17

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SIST EN 60068-2-65:2013
60068-2-65 © IEC:2013 – 3 –
Figure A.1 – Typical microphone arrangement around a specimen in a reverberation
chamber. 22
Figure A.2 – Typical microphone checkpoint arrangement around a long cylindrical
specimen . 25

Table 1 – Tolerances for acoustic measurement . 14
Table 2 – Overall sound pressure level and duration of exposure . 18
Table A.1 – Octave band/room volume relationship . 23
Table A.2 – Reverberation room, ratios of dimensions . 23
Table A.3 – Examples of sound sources with waveforms and typical power outputs. 28
Table A.4 – Typical OASPL and exposure durations . 28

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SIST EN 60068-2-65:2013
– 4 – 60068-2-65 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ENVIRONMENTAL TESTING –

Part 2-65: Tests –
Test Fg: Vibration –
Acoustically induced method


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60068-2-65 has been prepared by IEC technical committee 104:
Environmental conditions, classification and methods of test.
This second edition cancels and replaces the second edition, published in 1993, and
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– minor technical and editorial changes were made throughout the document as originally
requested by the DE National Committee;
– following comments at the CD stage, particularly from the UK National Committee,
significant technical and editorial additions were made to the standard for acoustic testing
employing the progressive wave tube technique.

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SIST EN 60068-2-65:2013
60068-2-65 © IEC:2013 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
104/591/FDIS 104/597/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.
A list of all the parts in the IEC 60068 series, published under the general title Environmental
testing, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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SIST EN 60068-2-65:2013
– 6 – 60068-2-65 © IEC:2013
INTRODUCTION
Acoustic noise may produce significant vibration in components and equipment. In the acoustic
noise field, sound pressure fluctuations impinge directly on the specimen and the response
may be different to that produced by mechanical excitation.
Items particularly sensitive to acoustic noise include relatively lightweight items whose
dimensions are comparable to an acoustic wavelength in the frequency range of interest and
whose mass per unit area is low, such as dish antennas and solar panels, electronic devices,
printed circuit boards, optical elements, etc.
Acoustic testing is applicable to components, equipment, functional units and other products,
hereinafter referred to as “specimens”, which are liable to be exposed to and/or are required to
function in conditions of high sound pressure levels. It should be noted that, under service
conditions, the specimen may be subjected to simultaneous mechanical and acoustical
excitation.
High sound pressure levels may be generated by jet engines and other aircraft propulsion
systems, rocket motors, high-powered gas circulators, turbulent gas flow around aircraft or
launchers, etc. This part of IEC 60068 deals with acoustic testing in compressible gases and
can also be used to simulate the excitation response caused by turbulence resulting from high-
velocity separated gas flows.
The intent of the test procedure contained in this standard is to produce a high intensity
acoustic noise field by either reverberant methods (known as reverberant chamber testing) or
by progressive wave methods (known as progressive wave tube testing).
Testing for the effects of vibration caused by acoustic noise demands a certain degree of
engineering judgement and this should be recognized both by the manufacturer/supplier and
the purchaser of the specimen. Based on the guidance provided in this standard, the writer of
the relevant specification is expected to select the most appropriate method of test and values
of severity, taking account of the nature of the specimen and its intended use.
Since the acoustic levels occurring during testing are high enough to be damaging to human
hearing, appropriate protective measures need to be taken to reduce the noise exposure of
operators performing the test to a level regarded as permissible from the standpoint of hearing
conservation.

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SIST EN 60068-2-65:2013
60068-2-65 © IEC:2013 – 7 –
ENVIRONMENTAL TESTING –

Part 2-65: Tests –
Test Fg: Vibration –
Acoustically induced method



1 Scope
This part of IEC 60068 provides standard procedures and guidance for conducting acoustic
tests in order to determine the ability of a specimen to withstand vibration caused by a
specified sound-pressure level environment to which it is, or is liable to be, subjected.
For sound pressure level environments of less than 120 dB acoustic tests are not normally
required.
This standard determines the mechanical weakness and/or degradation in the performance of
specimens and to use this information, in conjunction with the relevant specification, to decide
on their acceptability for use. The methods of test may also be used as a means of establishing
the mechanical robustness or fatigue resistance of specimens.
Two procedures are described for conducting tests and for measurement of the sound
pressure levels within the acoustic noise field and considers the need for measurement of the
vibration responses at specified points on the specimen. It also gives guidance for the
selection of the acoustic noise environment, spectrum, sound pressure level and duration of
exposure.
The progressive wave tube method is relevant to material where aerodynamic turbulence will
excite part, or all, of the total external surface. Such applications include aircraft panel
assemblies where the excitation exists on one side only. The reverberant chamber method is
relevant where it is preferable to induce vibration onto the entire external surface of equipment
by distributed excitation rather than fixed points by means of electro-dynamic shakers.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
IEC 61672-1, Electroacoustics – Sound level meters – Part 1: Specifications
ISO/IEC 17025:2005, General requirements for the competence of testing and calibration
laboratories
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

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SIST EN 60068-2-65:2013
– 8 – 60068-2-65 © IEC:2013
3.1.1
acoustic horn
tube with increasing cross-section of generally exponential envelope, used to couple an
acoustic source to the test volume, for example the inside of a reverberation room, thus
achieving the maximum transfer of sound energy
Note 1 to entry: Each acoustic horn has individual transfer characteristics which affect the sound spectrum.
3.1.2
analysis integration time
time duration over which a signal is averaged
Note 1 to entry: See Clause A.8.
3.1.3
bandwidth
difference between the nominal upper and lower cut-off frequencies
Note 1 to entry: It may be expressed
a) in hertz,
b) as a percentage of the pass-band centre frequency, or
c) as the interval between the upper and lower nominal cut-off frequencies in octaves.
3.1.4
overall sound pressure level
OASPL
value computed from the third-octave or octave band sound pressure levels L
i
m
L /10
i
L = 10 log 10
∑
G 10
i=1
where
L is the overall sound pressure level in dB;
G
L is the sound pressure level in the ith third-octave or octave band;
i
m is the number of third-octave or octave bands.
3.1.5
centre frequency
geometric mean of the nominal cut-off frequencies of a pass-band
Note 1 to entry: The nominal upper and lower cut-off frequencies of a filter pass-band are defined as those
frequencies above and below the frequency of maximum response of a filter at which the response to a sinusoidal
signal is 3 dB below the maximum response.
½
Note 2 to entry: The geometric mean is equal to (f × f ) , where f and f are the cut-off frequencies.
1 2 1 2
3.1.6
constant-bandwidth filter
filter which has a bandwidth of constant value when expressed in hertz; it is independent of the
centre frequency of the filter
3.1.7
cut-off frequency (of acoustic horn)
frequency below which an acoustic horn becomes increasingly ineffective
Note 1 to entry: This cut-off frequency is a main characteristic of an acoustic horn.

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SIST EN 60068-2-65:2013
60068-2-65 © IEC:2013 – 9 –
3.1.8
diffuse sound field
sound field which, in a given region, has statistically uniform energy density, for which the
directions of propagation at any point are randomly distributed
Note 1 to entry: In a diffuse sound field, the sound pressure level measured with a directional microphone would
give the same results whatever its orientation.
1
[SOURCE: IEC 60050-801:1994 [1] , definition 801-23-31, modified – Addition of the Note 1 to
entry]
3.1.9
electro-pneumatic transducer
hydraulic-pneumatic transducer
most generally employed laboratory source of acoustic noise to simulate sound pressure levels
encountered in a high operational ambient acoustic noise environment
Note 1 to entry: This transducer consists of a pneumatic transducer supplied with pressurized gas modulated by
an electromagnetic or hydraulic valve.
Note 2 to entry: This type of transducer provides a continuous spectrum of energy over a wide frequency band
with random amplitude distribution and is capable of providing a shaped sound spectrum to meet the specifications
in acoustic testing (see Clause A.5).
3.1.10
grazing incidence
angle between the direction of the acoustic wave and either the surface of the specimen and/or
the sensing surface of the acoustic transducer, 0 ° being parallel and 90 ° normal to the
surface
3.1.11
frequency interval
ratio of two frequencies
[SOURCE: IEC 60050-801:1994, definition 801-30-07]
3.1.11.1
octave
interval between two frequencies which have a ratio of 2
3.1.11.2
one-third octave
1/3
1/3
interval between two frequencies which have a ratio equal to 2
Note 1 to entry: Octave and third-octave frequency bands are defined by their geometric centre frequencies in
ISO 266 [2].
3.1.11.3
one-twelfth octave
1/12
1/12
interval between two frequencies which have a ratio equal to 2
3.1.12
measuring points
specific points in the sound field at which sound pressure is measured for the conduct of the
test
______________
1
Figures in square brackets refer to the bibliography.

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SIST EN 60068-2-65:2013
– 10 – 60068-2-65 © IEC:2013
Note 1 to entry: Measurements may be made at points within the specimen in order to assess its behaviour but
these are not considered as measuring points in the sense of this standard.
3.1.12.1
checkpoints
points located on a fictitious surface surrounding the specimen and at a fixed distance from it
3.1.12.2
reference points
points chosen from the checkpoints, whose signals are used to control the test so that the
requirements of this standard are satisfied
3.1.13
multipoint control
control achieved by using the average of the signals at the reference points
Note 1 to entry: When using multipoint control, each microphone signal relates to the sound pressure level at one
position. The average sound pressure level L can be computed as given in IEC 60050-801:1994, definition 801-
AV
31-36, when
n
L /10
1
i
L = 10 log 10
∑
AV 10
n
1
where
n is the number of reference points;
L is the sound pressure level in the ith third-octave or octave band.
i
3.1.14
narrowband frequency filter
band-pass filter for which the pass-band is generally smaller than third-octave
3.1.15
broadband frequency
wide band filter
band-pass filter for which the pass-band is relatively wide or broad, in general larger than an
octave
3.1.16
progressive wave tube
tube along which sound waves propagate from the acoustic source, which is coupled to a
suitable test section by an acoustic horn
Note 1 to entry: The tube is terminated by an acoustically absorptive termination placed at the end of the test
section to minimize reflection of the progressive acoustic waves in the frequency range of interest (see Clause A.2).
3.1.17
proportional-bandwidth filter
filter which has a bandwidth that is proportional to the frequency
Note 1 to entry: Octave bandwidth, third-octave bandwidth, etc. are typical bandwidths for proportional-bandwidth
filters.
3.1.18
reverberation chamber (or room)
chamber or room which has hard, highly reflective surfaces such that the sound field therein
becomes diffuse
Note 1 to entry: The geometry of the chamber or room may influence the test. Information on reverberant
chambers is given in Clause A.1.

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