ISO 9296:2017

INTERNATIONAL ISO
STANDARD 9296
Second edition
2017-08
Acoustics — Declared noise emission
values of information technology and
telecommunications equipment
Acoustique — Valeurs déclarées d’émission acoustique des
équipements liés aux technologies de l’information et aux
télécommunications
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
3.1 General definitions . 2
3.2 Definitions relating to acoustics . 3
3.3 Definitions relating to statistics . 4
4 Conformity requirements . 5
4.1 For declaration . 5
4.2 For verification . 6
5 Determination of the noise emission values to declare. 6
5.1 General . 6
5.2 Determination of the declared mean A-weighted sound power level, L .
WA,m 6
5.3 Determination of the declared mean A-weighted emission sound pressure level, L .
pA,m 7
5.4 Determination of the statistical adder for verification, K .
v 7
6 Presentation of declared noise emission values . 7
6.1 Required information . 7
6.2 Additional information . 8
7 Verification of the statistical upper limit A-weighted sound power level, L .8
WA,c
7.1 General . 8
7.2 Verification of L for a batch of equipment . 8
WA,c
Annex A (normative) Procedure for determining the statistical adder for verification, K .10
v
Annex B (informative) Examples of noise emission declarations .13
Annex C (informative) Character of noise .15
Bibliography .16
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
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electrotechnical standardization.
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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
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on the ISO list of patent declarations received (see www .iso .org/ patents).
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URL: w w w . i s o .org/ iso/ foreword .html
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This second edition cancels and replaces the first edition (ISO 9296:1988), which has been technically
revised, and in addition contains the following changes:
— the Normative references clause has been updated and certain references moved to the
Bibliography;
— a new Annex A has been added;
— a Bibliography has been added.
iv © ISO 2017 – All rights reserved

Introduction
Information on acoustical noise emission of information technology and telecommunications equipment
(ITT equipment) is needed by users, planners, manufacturers and authorities. This information is
required for comparison of the noise emissions from different products and for installation acoustics
planning and may be used for workplace noise immission requirements.
In order for equipment noise emission data to be useful, uniform methods are necessary for the
following purposes:
— Measurement of noise emission values
[1] [2]
ISO 7779 specifies procedures for determining sound power level based on ISO 3741 ISO 3744
[3]
and ISO 3745 (reverberation test room or hemi-anechoic room) and emission sound pressure
[7]
level based on ISO 11201.
— Determination of the noise emission values to be declared
[4]
ISO 4871 gives guidelines for the preparation of standards for deriving noise emission values for
[5,6]
declaration purposes, and the ISO 7574 series gives statistical methods for such determination.
This document is based on the above-mentioned International Standards.
— Presentation of declared noise emission values
For the presentation of declared noise emission values, it is of prime importance to declare
A-weighted sound power levels, L . It is recognized, however, that users still desire information
WA
on A-weighted emission sound pressure levels, L . Therefore, this document provides methods
pA
for declaration of both quantities. In the preparation of this document, divergent opinions have
been found between various national and international organisations as to the most useful way of
presenting noise emission values. In order to avoid any misunderstanding between presentation of
sound power levels (re 1 pW) in decibels and emission sound pressure levels (re 20 μPa) in decibels,
this document expresses sound power level values to be declared in bels and emission sound
pressure level values in decibels, to alleviate the divergent opinions mentioned.
As an option, methods for determination and presentation of subjective characteristics of noise
emission are presented in Annex C.
— Verification of declared noise emission values
[6]
ISO 7574-4 gives methods for the verification of a declared noise emission value. In this document,
the procedure is restricted to verifying the statistical upper limit A-weighted sound power level,
L , only.
WA,c
For continuity with ISO 9296:1988 and current practice, this document specifies bels as the unit
for declaring sound power levels. It should be noted, however, that the decision has been made to
change the unit to decibels in the next edition, and users of this document should begin to prepare
for this transition.
INTERNATIONAL STANDARD ISO 9296:2017(E)
Acoustics — Declared noise emission values of information
technology and telecommunications equipment
1 Scope
This document is applicable to information technology and telecommunications equipment.
It specifies:
a) for a batch of equipment, the method for determining the following values:
— the declared mean A-weighted sound power level, L ;
WA,m
— the declared mean A-weighted emission sound pressure level, L ;
pA,m
— the statistical adder for verification, K ;
v
— the statistical upper limit A-weighted sound power level, L ;
WA,c
b) how acoustical and product information is to be published electronically or in hard-copy format in
technical documents or other product literature supplied to users by the manufacturer or declarer;
c) the method for verifying the noise emission values that are declared by the manufacturer or
declarer.
NOTE The terms “manufacturer” and “declarer” are used in this document to represent any entity that
provides product noise emission information. For instance, a product supplier or importer who does not
manufacture the hardware, but offers noise emissions information, is also referred to a manufacturer or a
declarer as applicable, in this document.
The uniform methods in this document use the noise emission data obtained in accordance with
[4] [6]
ISO 7779, and the declaration and verification procedures detailed in ISO 4871 and ISO 7574-4.
The basic noise emission values to be declared are the declared mean A-weighted sound power levels,
L . Optionally, the declared mean A-weighted emission sound pressure levels at the operator
WA,m
or bystander positions, L , can be declared. These are arithmetic mean values based upon
pA,m
measurements on a random sample of equipment of the batch, in accordance with ISO 7779.
For verification purposes, an additional quantity is required to be declared: the statistical adder for
verification, K . This is a quantity that is added to the declared mean A-weighted sound power level,
v
L , and used in the verification section of this document to provide a consistent and predictable
WA,m
probability of acceptance for the batch of equipment.
The declared mean A-weighted sound power level for the batch of equipment permits comparison of
noise emissions between different products and permits predictions of installation or work-place noise
[9]
immission levels, as described in ECMA TR/27.
Although the most useful quantity for calculating immission levels due to one or more noise sources is
the A-weighted sound power level of the individual source(s), the A-weighted emission sound pressure
level may also be useful in estimating the immission level in the immediate vicinity of an isolated piece
of equipment.
To avoid confusion between sound power levels and emission sound pressure levels, the declared
mean A-weighted sound power level, L , is expressed in bels (B) and the declared mean A-weighted
WA,m
emission sound pressure level, L , is expressed in decibels (dB).
pA,m
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.
ISO 7779, Acoustics — Measurement of airborne noise emitted by information technology and
telecommunications equipment
3 Terms and definitions
For the purposes of thi
...