Acoustics - Determination of high-frequency sound power levels emitted by machinery and equipment (ISO 9295:2015)

ISO 9295:2015 specifies four methods for the determination of the sound power levels of high-frequency noise emitted by machinery and equipment in the frequency range covered by the octave band centred at 16 kHz, which includes frequencies between 11,2 kHz and 22,4 kHz. They are complementary to the methods described in ISO 3741 and ISO 3744. The first three methods are based on the reverberation test room technique. The fourth method makes use of a free field over a reflecting plane.
The test conditions which prescribe the installation and operation of the equipment are those specified in ISO 3741 or ISO 3744 as applicable.

Akustik - Bestimmung der hochfrequenten Schallleistungspegel von Maschinen und Geräten (ISO 9295:2015)

Diese Internationale Norm legt vier Verfahren zur Bestimmung der Schallleistungspegel von hochfrequenten Geräuschen fest, die von Maschinen und Geräten im durch das Oktavband mit der Mittenfrequenz von 16 kHz abgedeckten Frequenzbereich abgestrahlt werden, welches die Frequenzen zwischen 11,2 kHz und 22,4 kHz umfasst. Sie ergänzen die in ISO 3741 und ISO 3744 enthaltenen Verfahren. Die ersten drei Verfahren beruhen auf dem Hallraumverfahren. Das vierte Verfahren nutzt ein Freifeld über einer reflektierenden Ebene.
Die Prüfbedingungen, die die Aufstellung und den Betrieb der Geräte festlegen, sind je nach Zutreffen in ISO 3741 oder ISO 3744 festgelegt.

Acoustique - Détermination des niveaux de puissance acoustique à haute fréquence émis par les machines et équipements (ISO 9295:2015)

ISO 9295:2015 spécifie quatre méthodes pour la détermination des niveaux de puissance acoustique du bruit à haute fréquence émis par les machines et équipements dans le domaine de fréquences couvert par la bande d'octave centrée sur 16 kHz, qui inclut les fréquences comprises entre 11,2 kHz et 22,4 kHz. Ces méthodes sont complémentaires aux méthodes décrites dans l'ISO 3741 et l'ISO 3744. Les trois premières méthodes reposent sur la technique en salle d'essai réverbérante. La quatrième méthode fait appel à un champ libre au-dessus d'un plan réfléchissant.
Les conditions d'essai qui déterminent l'installation et le fonctionnement des équipements sont celles spécifiées dans l'ISO 3741 ou l'ISO 3744, selon le cas.

Akustika - Določanje visokofrekvenčnih ravni zvočne moči naprav in opreme (ISO 9295:2015)

Ta mednarodni standard določa štiri metode za določanje visokofrekvenčnih ravni zvočne moči
naprav in opreme v frekvenčnem razponu, ki zajema oktavni pas s srednjo frekvenco 16 kHz, kar vključuje frekvence med 11,2 kHz in 22,4 kHz. Te metode dopolnjujejo metode, opisane v standardih ISO 3741 in ISO 3744. Prve tri metode temeljijo na tehniki odmeva v preskusnem prostoru. Pri četrti metodi se uporablja prosto polje nad odbojno ravnino. Preskusni pogoji, predpisani za namestitev in delovanje opreme, so opredeljeni v standardu ISO 3741 ali ISO 3744, kot je primerno.

General Information

Status
Published
Publication Date
19-May-2015
Technical Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing

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SLOVENSKI STANDARD
SIST EN ISO 9295:2015
01-oktober-2015
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SIST EN 29295:1999
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Acoustics - Determination of high-frequency sound power levels emitted by machinery

and equipment (ISO 9295:2015)
Akustik - Bestimmung der hochfrequenten Schallleistungspegel von Maschinen und
Geräten (ISO 9295:2015)

Acoustique - Détermination des niveaux de puissance à haute fréquence émis par les

machines et équipements (ISO 9295:2015)
Ta slovenski standard je istoveten z: EN ISO 9295:2015
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
35.020 Informacijska tehnika in Information technology (IT) in
tehnologija na splošno general
SIST EN ISO 9295:2015 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 9295:2015
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SIST EN ISO 9295:2015
EUROPEAN STANDARD
EN ISO 9295
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2015
ICS 17.140.20; 35.020 Supersedes EN 29295:1991
English Version
Acoustics - Determination of high-frequency sound power levels
emitted by machinery and equipment (ISO 9295:2015)

Acoustique - Détermination des niveaux de puissance Akustik - Bestimmung der hochfrequenten

acoustique à haute fréquence émis par les machines et Schallleistungspegel von Maschinen und Geräten (ISO

équipements (ISO 9295:2015) 9295:2015)
This European Standard was approved by CEN on 21 February 2015.

CEN 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 CEN 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 CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same

status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9295:2015 E

worldwide for CEN national Members.
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SIST EN ISO 9295:2015
EN ISO 9295:2015 (E)
Contents Page

Foreword ..............................................................................................................................................................3

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SIST EN ISO 9295:2015
EN ISO 9295:2015 (E)
Foreword

This document (EN ISO 9295:2015) has been prepared by Technical Committee ISO/TC 43 “Acoustics” in

collaboration with Technical Committee CEN/TC 211 “Acoustics” the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical

text or by endorsement, at the latest by November 2015, and conflicting national standards shall be withdrawn

at the latest by November 2015.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 29295:1991.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech

Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 9295:2015 has been approved by CEN as EN ISO 9295:2015 without any modification.

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SIST EN ISO 9295:2015
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SIST EN ISO 9295:2015
INTERNATIONAL ISO
STANDARD 9295
Second edition
2015-05-15
Acoustics — Determination of high-
frequency sound power levels emitted
by machinery and equipment
Acoustique — Détermination des niveaux de puissance acoustique à
haute fréquence émis par les machines et équipements
Reference number
ISO 9295:2015(E)
ISO 2015
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SIST EN ISO 9295:2015
ISO 9295:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
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SIST EN ISO 9295:2015
ISO 9295:2015(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Conformity requirements ........................................................................................................................................................................... 1

5 Requirements for measurements in a reverberation test room ......................................................................... 1

5.1 General ........................................................................................................................................................................................................... 1

5.2 Meteorological conditions ............................................................................................................................................................. 2

5.3 Instrumentation ..................................................................................................................................................................................... 2

5.4 Installation and orientation of microphone .................................................................................................................. 2

5.5 Installation and orientation of equipment ...................................................................................................................... 3

5.6 Calibration of measurement system ..................................................................................................................................... 3

5.7 Measurement of sound pressure level ................................................................................................................................ 3

6 Method using measured reverberation time .......................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Measurement of reverberation time .................................................................................................................................... 5

6.3 Calculation of room absorption ................................................................................................................................................ 5

6.4 Installation of microphone and equipment ................................................................................................................... 5

6.5 Measurement of sound pressure level ................................................................................................................................ 5

6.6 Calculation of sound power level ............................................................................................................................................ 6

7 Method using calculated air absorption ...................................................................................................................................... 6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Calculation of room constant ...................................................................................................................................................... 6

7.3 Installation of microphone and equipment ................................................................................................................... 6

7.4 Measurement of sound pressure level ................................................................................................................................ 6

7.5 Calculation of sound power level ............................................................................................................................................ 7

8 Method using a reference sound source ...................................................................................................................................... 8

8.1 Reference sound source .................................................................................................................................................................. 8

8.2 Installation of microphone and equipment ................................................................................................................... 8

8.3 Installation of reference sound source ............................................................................................................................... 9

8.4 Measurement of sound pressure level ................................................................................................................................ 9

8.5 Calculation of sound power level ............................................................................................................................................ 9

8.5.1 Equipment emitting broad-band noise ........................................................................................................ 9

8.5.2 Equipment emitting discrete tone(s) ..........................................................................................................10

9 Method using a free field over a reflecting plane ............................................................................................................10

9.1 General ........................................................................................................................................................................................................10

9.2 Meteorological conditions ..........................................................................................................................................................10

9.3 Instrumentation ..................................................................................................................................................................................11

9.4 Installation and orientation of microphone ...............................................................................................................11

9.5 Installation of equipment ...........................................................................................................................................................11

9.6 Calibration of measurement system ..................................................................................................................................11

9.7 Measurement of sound pressure level .............................................................................................................................12

9.8 Calculation of surface sound pressure level and sound power level .....................................................12

10 Calculation of sound power level under reference meteorological conditions ...............................13

10.1 Reverberation rooms ......................................................................................................................................................................13

10.2 Hemi-anechoic rooms ....................................................................................................................................................................13

11 Measurement uncertainty .......................................................................................................................................................................13

12 Information to be recorded ....................................................................................................................................................................13

© ISO 2015 – All rights reserved iii
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SIST EN ISO 9295:2015
ISO 9295:2015(E)

12.1 General ........................................................................................................................................................................................................13

12.2 Equipment under test ....................................................................................................................................................................13

12.3 Acoustic environment ....................................................................................................................................................................14

12.4 Instrumentation ..................................................................................................................................................................................14

12.5 Acoustical data .....................................................................................................................................................................................14

13 Information to be reported ....................................................................................................................................................................14

Annex A (normative) Calculation of air absorption coefficient .............................................................................................16

Bibliography .............................................................................................................................................................................................................................18

iv © ISO 2015 – All rights reserved
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SIST EN ISO 9295:2015
ISO 9295:2015(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any

patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT), see the following URL: Foreword — Supplementary information.

The committee responsible for this document is ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.

This second edition cancels and replaces the first edition (ISO 9295:1988), which has been technically revised.

© ISO 2015 – All rights reserved v
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SIST EN ISO 9295:2015
ISO 9295:2015(E)
Introduction

Some machinery and equipment emit high-frequency noise which might be broad-band noise (e.g. paper

noise of high-speed printing) or narrow-band noise and discrete tones (e.g. noise of switching power

supplies and video display units or medical devices).

This International Standard specifies methods for the determination of the sound power levels in the

frequency range covered by the octave band centred at 16 kHz. The measured levels are not frequency-

weighted. The principal objective of this International Standard is to prescribe methods for determining

the sound power levels and frequencies of tones which are contained within the 16 kHz octave band.

vi © ISO 2015 – All rights reserved
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SIST EN ISO 9295:2015
INTERNATIONAL STANDARD ISO 9295:2015(E)
Acoustics — Determination of high-frequency sound power
levels emitted by machinery and equipment
1 Scope

This International Standard specifies four methods for the determination of the sound power levels

of high-frequency noise emitted by machinery and equipment in the frequency range covered by the

octave band centred at 16 kHz, which includes frequencies between 11,2 kHz and 22,4 kHz. They are

complementary to the methods described in ISO 3741 and ISO 3744. The first three methods are based on

the reverberation test room technique. The fourth method makes use of a free field over a reflecting plane.

The test conditions which prescribe the installation and operation of the equipment are those specified

in ISO 3741 or ISO 3744 as applicable.
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.

ISO 3741, Acoustics — Determination of sound power levels and sound energy levels of noise sources using

sound pressure — Precision methods for reverberation test rooms

ISO 3744, Acoustics — Determination of sound power levels and sound energy levels of noise sources using

sound pressure — Engineering methods for an essentially free field over a reflecting plane

ISO 6926, Acoustics — Requirements for the performance and calibration of reference sound sources used

for the determination of sound power levels

ISO 9613-1, Acoustics — Attenuation of sound during propagation outdoors — Part 1: Calculation of the

absorption of sound by the atmosphere
3 Terms and definitions

For the purpose of this document, the terms and definitions given in ISO 3741 and ISO 3744 apply.

4 Conformity requirements

A method for the measurement of high-frequency noise is in conformance with this International

Standard if it satisfies all the mandatory requirements of one of the four methods described herein

specified in Clauses 6 to 9, and if the information recorded and reported is as specified in Clauses 12 and

13, respectively.
5 Requirements for measurements in a reverberation test room
5.1 General

This International Standard describes three methods using the reverberation test room technique of

ISO 3741. The first and the second methods are usually called “direct methods” because they use directly

measured or calculated reverberation times. The third method is a so-called “comparison method”.

A calibrated reference sound source is used from which the sound power levels of the equipment are

determined by comparison.
© ISO 2015 – All rights reserved 1
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SIST EN ISO 9295:2015
ISO 9295:2015(E)

All three methods require a determination of the mean time-averaged sound pressure level in the

reverberant field.

As instrumentation and basic measurement techniques are the same for all three methods, they are

summarized in 5.3 to 5.7. Additional requirements specific to each method are given separately. For

additional requirements on instrumentation, see ISO 3741.
5.2 Meteorological conditions

The air absorption in the reverberation test room varies with temperature and humidity, particularly

at frequencies above 1 000 Hz. The temperature, θ, in degrees Celsius (°C) and the relative humidity, h ,

expressed as a percentage, shall be controlled during the sound pressure level measurements.

The product, h × (θ + 5 °C), shall not vary by more than ±10 % during the measurements.

For equipment whose noise emissions intentionally vary with ambient temperature (e.g. by varying the

speeds of air moving devices), the room temperature during the test measurement shall be 23 °C ± 2 °C

or, if the room temperature is outside these limits, the fan shall be adjusted to the speed for an ambient

temperature of 23 °C ± 2 °C.
The following conditions are recommended:
— Static pressure: 86 kPa to 106 kPa;
— Temperature: 15 °C to 30 °C;
— Relative humidity: 40 % to 70 %.

NOTE As indicated in Tables 1 and 2 for the temperature range of 18 °C to 27 °C, higher temperatures and

higher humidity will tend to minimize the effects of atmospheric absorption.
5.3 Instrumentation

The sound measuring system, including the microphone, should have a flat frequency response for

random incident sound in the 16 kHz octave band. The microphone response shall be corrected to give

a flat frequency response within in the 16 kHz octave band. The tolerances after correction shall be

within ±1,0 dB in the frequency range of 11,2 kHz to 22,4 kHz.

NOTE 1 To meet this requirement, a microphone with a diameter of 13,2 mm or less is usually required.

When the noise of the equipment under test is broad-band in character without any significant discrete

tone, an analyser with a bandwidth of one-third-octave or less shall be used. When the noise of the

equipment under test contains discrete tone(s), a narrow-band analyser, which provides bandwidths of

less than one-third-octave in width, shall be used to determine the frequency of the tone(s).

NOTE 2 For narrow-band analysis, an analyser with a bandwidth equal to, or less than, one twelfth octave

is appropriate. Digital analysers using fast Fourier transform (FFT) or equivalent techniques can be useful,

particularly when the analyser combines narrow-band analysis and averaging.
5.4 Installation and orientation of microphone

The microphone shall be mounted at the end of a rotating boom traversing a circle with a diameter of at

least 2 m. In order to reduce the influence of the direct field on the measured sound pressure level, the

microphone shall be mounted pointing in such a way that the normal to its diaphragm is parallel to the

axis of rotation with the microphone diaphragm perpendicular to direction of the equipment under test.

The period of rotation shall be as required by ISO 3741.

Longer paths and traversing periods than the minimum values can be used to reduce the background noise

of the drive mechanism, and to minimize modulation of any discrete tone(s) due to the moving microphone.

2 © ISO 2015 – All rights reserved
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SIST EN ISO 9295:2015
ISO 9295:2015(E)

Care shall be taken to ensure that there is no electrical pick-up by the measurement instrumentation

which can interfere with the sound pressure level measurement.

NOTE A test with a dummy microphone, and with the equipment under test in operation, can determine

the influence on the noise floor of the instrumentation. Alternatively, if no dummy microphone is available

without moving the microphone from the measurement position, this influence can be determined by sealing

the microphone and pressure equalization vent in an electrical non-conductive enclosure providing an acoustical

attenuation of at least 10 dB at all frequencies of interest.
5.5 Installation and orientation of equipment

Equipment shall be placed on the floor of the reverberation test room, at least 1 m from any wall, and at

least 1,8 m from the point of closest approach of the microphone.
Four orientations of the equipment shall be used as follows.
— Operator side facing the centre of the microphone path.

— Equipment turned clockwise by 90° from its initial position about a vertical axis through its centre.

— Equipment turned clockwise by 180° from its initial position about a vertical axis through its centre.

— Equipment turned clockwise by 270° from its initial position about a vertical axis through its centre.

Alternatively, equipment shall be placed on a turntable and the turntable shall be revolved during

the measurements. The motion of the turntable shall not be synchronous with the rotation of the

microphone boom.
5.6 Calibration of measurement system

Before the measurement of the equipment noise, the measurement set-up shall be calibrated in

accordance with ISO 3741. Calibration at a single frequency is sufficient if the frequency response of the

entire system, including the frequency range of the 16 kHz octave band, is checked at intervals of not

more than two years.

If an FFT analyser is calibrated with a single-frequency calibrator, care shall be taken to have all major

sideband levels included in the calibration level.
5.7 Measurement of sound pressure level

The sound pressure level is measured in one-third-octave bands or, if discrete tones are present, in

narrow bands which include the discrete tones. Measurements of the time-averaged sound pressure level

along the circular microphone path shall be carried out for each frequency band within the frequency

range of interest. The following data shall be obtained:
a) the band time-averaged sound pressure level with the equipment in operation;

b) the band time-averaged sound pressure levels of the background noise (including noise produced

by ancillary equipment, if any); and

c) the band time-averaged sound pressure levels of the reference sound source (if required,

see Clause 8).

True integration-averaging during a full sweep of the microphone is the preferred method. When using

a narrow-band analyser that performs the analysis in consecutive time periods, each time period shall

correspond to one revolution. The influence of measurement duration and corrections for background

noise shall be taken into account in accordance with ISO 3741.

When FFT analysers are used, the analysis time is typically greater than the individual time window.

For this reason, the total measurement time shall be increased, or individual measurements shall be

repeated for three revolutions of the boom, each for a different starting point.
© ISO 2015 – All rights reserved 3
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SIST EN ISO 9295:2015
ISO 9295:2015(E)
The mean value, L , of N measurements of the time-averaged sound pressure l
...

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