SIST-TS ISO/TS 7849-2:2014

TECHNICAL ISO/TS
SPECIFICATION 7849-2
First edition
2009-03-15
Acoustics — Determination of airborne
sound power levels emitted by machinery
using vibration measurement —
Part 2:
Engineering method including
determination of the adequate radiation
factor
Acoustique — Détermination des niveaux de puissance acoustique
aériens émis par les machines par mesurage des vibrations —
Partie 2: Méthode d'expertise incluant la détermination d'un facteur
de rayonnement approprié
Reference number
©
ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Principle. 4
5 Measuring instrumentation. 5
5.1 General. 5
5.2 Vibration transducer. 5
5.3 Non-contacting transducers. 6
5.4 Amplifier and filter . 6
5.5 Integrator . 6
5.6 Calibration . 6
6 Installation and operation of source under test . 7
6.1 General. 7
6.2 Description of the machine. 7
6.3 Installation . 7
6.4 Operating conditions. 7
7 Determination of the vibratory velocity on the vibrating measurement surface . 7
7.1 General. 7
7.2 Vibrating measurement surface . 8
7.3 Number of measurement positions . 8
7.4 Environmental conditions. 9
7.5 Measurement procedure . 9
7.6 Mounting of the vibration transducer. 9
8 Determination of the machinery specific frequency band radiation factor. 10
9 Calculations. 11
9.1 Correction for extraneous vibratory velocity. 11
9.2 Determination of the mean vibratory velocity level on the vibrating measurement surface. 12
9.3 Calculation of the airborne sound power level caused by radiation of structure vibration
generated sound. 13
10 Measurement uncertainty . 13
11 Information to be recorded . 14
11.1 Machine under test . 14
11.2 Measurement conditions . 15
11.3 Measuring instrumentation. 15
11.4 Acoustical data . 15
Annex A (informative) Use of the vibration transducer. 16
Annex B (normative) Procedures for calculating A-weighted sound power levels from octave
band or one-third-octave band levels. 18
Annex C (informative) Recommendations concerning the frequency bands of interest . 20
Annex D (informative) Determination of the vibratory velocity level from the vibratory acceleration
level . 21
Annex E (informative) Guidance on the development of information on measurement uncertainty. 23
Bibliography . 26
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
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In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of document:
⎯ an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
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⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
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International Standard or be withdrawn.
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.
ISO/TS 7849-2 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This first edition of ISO/TS 7849-2, together with ISO/TS 7849-1, cancel and replace the first edition of
ISO/TR 7849:1987, which has been technically revised.
ISO/TS 7849 consists of the following parts, under the general title Acoustics — Determination of airborne
sound power levels emitted by machinery using vibration measurement:
⎯ Part 1: Survey method using a fixed radiation factor
⎯ Part 2: Engineering method including determination of the adequate radiation factor
The following part is under preparation:
⎯ Part 3: Amplitude and phase measurements
iv © ISO 2009 – All rights reserved

Introduction
This part of ISO/TS 7849 gives a procedure for the determination of the sound power of the airborne noise
caused by machinery vibration, including determination and application of the adequate radiation factor.
The determination of airborne noise emission of a machine by measuring vibration of the machine's outer
surface may be of interest when:
⎯ undesired background noise (e.g. noise from other machines or sound reflected by room boundaries) is
high compared with the noise radiated directly by the machine under test;
⎯ noise radiated by structure vibration is to be separated from noise of aerodynamic origin;
⎯ noise radiated by structure vibration is high compared to the aerodynamic component so that the total
noise radiation is predominantly affected by the structure vibration;
[14]
⎯ sound intensity measurement techniques [ISO 9614 (all parts) ] cannot easily be applied;
⎯ structure vibration generated noise from only a part of a machine, or from a component of a machine set,
is to be determined in the presence of noise from the other parts of the whole source.
ISO/TS 7849 (all parts) describes methods for the determination of the airborne noise emission of a machine
caused by vibration of its outer surface, expressed by the associated airborne sound power being related to
normalized meteorological conditions. This airborne sound power is determined under the assumption that
this quantity is proportional to the mean square value of the normal component of the velocity averaged over
the area of the vibrating outer surface of the machine, and is directly proportional to the area of the vibrating
surface.
The calculation of the airborne sound power needs data of the radiation factor, ε, as a function of frequency
for the machine under test. These values can be taken as unity (ε = 1) independently of frequency, yielding an
upper limit for the sound power (see ISO/TS 7849-1); or, it can be determined for specific machines as
described in this part of ISO/TS 7849.
Details of ISO/TS 7849 (all parts) are given in the foreword.

TECHNICAL SPECIFICATION ISO/TS 7849-2:2009(E)

Acoustics — Determination of airborne sound power levels
emitted by machinery using vibration measurement —
Part 2:
Engineering method including determination of the adequate
radiation factor
1 Scope
This part of ISO/TS 7849 gives basic requirements for a reproducible method for the determination of the
sound power level of the noise emitted by machinery or equipment by using surface vibration measurements,
together with the knowledge of the machinery specific sound radiation factor in the frequency bands. The
method is only applicable to noise which is emitted by vibrating surfaces of solid structures and not to noise
generated aerodynamically.
This vibration measurement method is especially applicable in cases where accurate direct airborne noise
[7] [8] [14]
measurements, e.g. as specified in ISO 3746 , ISO 3747 , and ISO 9614 (all parts) , are not possible
because of high back
...