Acoustics - Determination of airborne sound power levels emitted by machinery using vibration measurement - Part 1: Survey method using a fixed radiation factor (ISO/TS 7849-1:2009)

This part of ISO/TS 7849 gives basic requirements for reproducible methods for the determination of an upper limit for the A-weighted sound power level of the noise emitted by machinery or equipment by using surface vibration measurements. 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 measurements, e.g. as specified in ISO 3746[7], ISO 3747[8], and ISO 9614 (all parts)[12], are not possible because of high background noise or other parasitic environmental interferences; or if a distinction is required between the total radiated sound power and its structure vibration generated component.
NOTE 1   One of the applications of this part of ISO/TS 7849 is the distinction between the radiation of airborne sound power generated by structure vibration and the aerodynamic sound power components. Such a distinction is not feasible with ISO 3746[7] and ISO 9614 (all parts)[12].
NOTE 2   Problems can occur if the noise is generated by small parts of machinery surfaces (sliding contacts, e.g. slip ring brush or the commutator and the brush in electrical machines).
The methods described in this part of ISO/TS 7849 apply mainly to processes that are stationary with respect to time.

Akustik - Bestimmung der von Maschinen abgestrahlten Luftschallleistungspegel durch Schwingungsmessung - Teil 1: Verfahren der Genauigkeitsklasse 3 mit festem Strahlungsfaktor (ISO/TS 7849-1:2009)

Acoustique - Détermination des niveaux de puissance acoustique aériens émis par les machines par mesurage des vibrations - Partie 1: Méthode de contrôle employant un facteur de rayonnement fixe (ISO/TS 7849-1:2009)

Akustika - Določanje ravni zvočnih moči v zraku, ki jih povzročajo stroji, z merjenjem vibracij - 1. del: Informativna metoda s fiksnim faktorjem sevanja (ISO/TS 7849-1:2009)

General Information

Status
Published
Public Enquiry End Date
22-Dec-2021
Publication Date
15-Jun-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
19-May-2022
Due Date
24-Jul-2022
Completion Date
16-Jun-2022

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SLOVENSKI STANDARD
SIST-TS CEN ISO/TS 7849-1:2022
01-julij-2022
Akustika - Določanje ravni zvočnih moči v zraku, ki jih povzročajo stroji, z
merjenjem vibracij - 1. del: Informativna metoda s fiksnim faktorjem sevanja
(ISO/TS 7849-1:2009)

Acoustics - Determination of airborne sound power levels emitted by machinery using

vibration measurement - Part 1: Survey method using a fixed radiation factor (ISO/TS

7849-1:2009)

Akustik - Bestimmung der von Maschinen abgestrahlten Luftschallleistungspegel durch

Schwingungsmessung - Teil 1: Verfahren der Genauigkeitsklasse 3 mit festem
Strahlungsfaktor (ISO/TS 7849-1:2009)

Acoustique - Détermination des niveaux de puissance acoustique aériens émis par les

machines par mesurage des vibrations - Partie 1: Méthode de contrôle employant un

facteur de rayonnement fixe (ISO/TS 7849-1:2009)
Ta slovenski standard je istoveten z: CEN ISO/TS 7849-1:2022
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
17.160 Vibracije, meritve udarcev in Vibrations, shock and
vibracij vibration measurements
SIST-TS CEN ISO/TS 7849-1:2022 en,fr,de

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

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SIST-TS CEN ISO/TS 7849-1:2022
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SIST-TS CEN ISO/TS 7849-1:2022
CEN ISO/TS 7849-1
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
February 2022
TECHNISCHE SPEZIFIKATION
ICS 17.140.20
English Version
Acoustics - Determination of airborne sound power levels
emitted by machinery using vibration measurement - Part
1: Survey method using a fixed radiation factor (ISO/TS
7849-1:2009)

Acoustique - Détermination des niveaux de puissance Akustik - Bestimmung der von Maschinen

acoustique aériens émis par les machines par abgestrahlten Luftschallleistungspegel durch

mesurage des vibrations - Partie 1: Méthode de Schwingungsmessung - Teil 1: Verfahren der

contrôle employant un facteur de rayonnement fixe Genauigkeitsklasse 3 mit festem Strahlungsfaktor

(ISO/TS 7849-1:2009) (ISO/TS 7849-1:2009)

This Technical Specification (CEN/TS) was approved by CEN on 7 February 2022 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to

submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS

available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in

parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, 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: Rue de la Science 23, B-1040 Brussels

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 7849-1:2022 E

worldwide for CEN national Members.
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SIST-TS CEN ISO/TS 7849-1:2022
CEN ISO/TS 7849-1:2022 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST-TS CEN ISO/TS 7849-1:2022
CEN ISO/TS 7849-1:2022 (E)
European foreword

The text of ISO/TS 7849-1:2009 has been prepared by Technical Committee ISO/TC 43 "Acoustics” of

the International Organization for Standardization (ISO) and has been taken over as CEN ISO/TS 7849-

1:2022 by Technical Committee CEN/TC 211 “Acoustics” the secretariat of which is held by DIN.

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

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

Any feedback and questions on this document should be directed to the users’ national standards body.

A complete listing of these bodies can be found on the CEN website.

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

following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO/TS 7849-1:2009 has been approved by CEN as CEN ISO/TS 7849-1:2022 without any

modification.
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SIST-TS CEN ISO/TS 7849-1:2022
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SIST-TS CEN ISO/TS 7849-1:2022
TECHNICAL ISO/TS
SPECIFICATION 7849-1
First edition
2009-03-15
Acoustics — Determination of airborne
sound power levels emitted by machinery
using vibration measurement —
Part 1:
Survey method using a fixed radiation
factor
Acoustique — Détermination des niveaux de puissance acoustique
aériens émis par les machines par mesurage des vibrations —
Partie 1: Méthode de contrôle employant un facteur de rayonnement
fixe
Reference number
ISO/TS 7849-1:2009(E)
ISO 2009
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)
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Published in Switzerland
ii © ISO 2009 – All rights reserved
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)
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................................................................................................................ 5

5.4 Amplifier ................................................................................................................................................ 6

5.5 Integrator ............................................................................................................................................... 6

5.6 Calibration ............................................................................................................................................. 6

6 Installation and operation of source under test ................................................................................ 6

6.1 General................................................................................................................................................... 6

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 .......................................................................................................... 7

7.3 Number of measurement positions .................................................................................................... 8

7.4 Environmental conditions.................................................................................................................... 8

7.5 Measurement procedure ...................................................................................................................... 9

7.6 Mounting of the vibration transducer................................................................................................. 9

8 Calculations........................................................................................................................................... 9

8.1 Correction for extraneous vibratory velocity..................................................................................... 9

8.2 Determination of the mean A-weighted vibratory velocity level on the vibrating

measurement surface......................................................................................................................... 10

8.3 Calculation of the upper limit of the A-weighted airborne sound power level caused by

radiation of structure vibration generated sound ........................................................................... 11

9 Measurement uncertainty .................................................................................................................. 11

10 Information to be recorded ................................................................................................................ 13

10.1 Machine under test ............................................................................................................................. 13

10.2 Measurement conditions ................................................................................................................... 13

10.3 Measuring instrumentation................................................................................................................ 13

10.4 Acoustical data ................................................................................................................................... 13

Annex A (informative) Use of the vibration transducer................................................................................ 14

Annex B (informative) Guidance on the development of information on measurement uncertainty...... 16

Bibliography ..................................................................................................................................................... 19

© ISO 2009 – All rights reserved iii
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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

of the parent committee casting a vote;

⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical

committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting

a vote.

An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a

further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is

confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an

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 7849-1 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.

This first edition of ISO/TS 7849-1, together with ISO/TS 7849-2, 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
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)
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.

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;
[12]

⎯ 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 machine.

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 A-weighted 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 in principle. For this part of

ISO/TS 7849 a radiation factor of 1 is assumed allowing the determination of an upper limit for the radiated

A-weighted sound power level. For typical machines this upper limit may exceed the true A-weighted sound

[12]

power level determined by the intensity procedure of ISO 9614 (all parts) by up to 10 dB. The A-weighted

sound power level determined according to this part of ISO/TS 7849 can be used for sound power level

comparison of relevant vibrating machinery noise of the same family with similar design.

© ISO 2009 – All rights reserved v
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SIST-TS CEN ISO/TS 7849-1:2022
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SIST-TS CEN ISO/TS 7849-1:2022
TECHNICAL SPECIFICATION ISO/TS 7849-1:2009(E)
Acoustics — Determination of airborne sound power levels
emitted by machinery using vibration measurement —
Part 1:
Survey method using a fixed radiation factor
1 Scope

This part of ISO/TS 7849 gives basic requirements for reproducible methods for the determination of an upper

limit for the A-weighted sound power level of the noise emitted by machinery or equipment by using surface

vibration measurements. 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] [12]

measurements, e.g. as specified in ISO 3746 , ISO 3747 , and ISO 9614 (all parts) , are not possible

because of high background noise or other parasitic environmental interferences; or if a distinction is required

between the total radiated sound power and its structure vibration generated component.

NOTE 1 One of the applications of this part of ISO/TS 7849 is the distinction between the radiation of airborne sound

power generated by structure vibration and the aerodynamic sound power components. Such a distinction is not feasible

[7] [12]
with ISO 3746 and ISO 9614 (all parts) .

NOTE 2 Problems can occur if the noise is generated by small parts of machinery surfaces (sliding contacts, e.g. slip

ring brush or the commutator and the brush in electrical machines).

The methods described in this part of ISO/TS 7849 apply mainly to processes that are stationary with respect

to time.
2 Normative references

The following referenced documents are indispensable for the application 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 5348, Mechanical vibration and shock — Mechanical mounting of accelerometers

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

measurement (GUM:1995)
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
© ISO 2009 – All rights reserved 1
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
structure vibration generated sound
airborne sound caused by structure vibration in the audible frequency range

NOTE For the purposes of this part of ISO/TS 7849, structure vibration generated sound is determined either from

the vibratory velocity or the vibratory acceleration of the surface of the solid structure.

3.2
machine

〈airborne sound power level measurement〉 equipment which incorporates a single or several noise sources

3.3
vibratory velocity

root-mean square (r.m.s.) value of the component of the velocity of a vibrating surface in the direction normal

to the surface

NOTE 1 The vibratory velocity, v, is the time integral of the vibratory acceleration, whose r.m.s. value is given for

sinusoidal vibration by:
v = (1)
2πf
where
a is the r.m.s. acceleration;
f is the frequency.

The vibratory velocity, v, is the time derivative of the vibratory displacement, s, ds/dt. For sinusoidal vibration, the r.m.s.

velocity, v, is given by:
vf=π2s (2)
where s is the r.m.s. displacement.

NOTE 2 In this part of ISO/TS 7849, the vibratory velocity is usually applied with A-weighting, denoted v .

3.4
A-weighted vibratory velocity level

ten times the logarithm to the base 10 of the ratio of the square of the r.m.s. value of the A-weighted vibratory

velocity, v , to the square of a reference value, v , expressed in decibels:
A 0
L = 10 lg dB (3)
2 © ISO 2009 – All rights reserved
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)
where

v is the A-weighted r.m.s. value of the vibratory velocity, in metres per second ;

–8 2)
v is the reference value for the velocity and is equal to 5 × 10 m/s .

NOTE For airborne and structure vibration generated sound, the reference value, v = 50 nm/s has the property that it

−5 −12 2

leads, together with p = 2 × 10 Pa, to the reference value of the intensity level I = 1 × 10 W/m and to the

0 0
characteristic impedance of air by p /v = 400 N s/m .
0 0
3.5
A-weighted radiation factor
factor expressing the efficiency of sound radiation given by:
ε = (4)
Z Sv
where

P is the A-weighted airborne sound power emitted by the vibrating surface of the machine,

[12]
determined according to ISO 9614 (all parts) ;

S is the area of the defined outer surface of the machine under test (vibrating measurement surface;

see 3.8);

v is the squared A-weighted r.m.s. value of the vibratory velocity averaged over S;

Z is the characteristic impedance of air.

NOTE The four quantities ε , P , v , and Z relate to the same period of time and to the same meteorological

A A c
conditions (atmospheric temperature, θ, and barometric pressure, B).
3.6
A-weighted airborne sound power level

ten times the logarithm to the base 10 of the ratio of the A-weighted airborne sound power emitted by the

surface of a machine, P , to a reference value, P , expressed in decibels
A 0
L = 10 lg dB (5)
W A
–12
where the reference value, P , is 10 W
3.7
upper limit of A-weighted airborne sound power level
WA,max

A-weighted airborne sound power level determined in accordance with the method described in this part of

ISO/TS 7849

1) A subscript “eff” is dropped, since only r.m.s. values are used throughout this part of ISO/TS 7849.

[1] −9 −8

2) In ISO 1683 , two reference values for the velocity level are mentioned: v = 10 m/s and 5 × 10 m/s. The latter is

intended for cases of airborne and structure vibration generated sound and is therefore used in this part of ISO/TS 7849. A

choice of v = 10 m/s results in a vibratory velocity level which is 34 dB higher than the level used in this part of

ISO/TS 7849. Therefore, if v = 10 m/s is used, subtract 34 dB from the right-hand sides of Equations (7), (8),

and (11).
© ISO 2009 – All rights reserved 3
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)
3.8
vibrating measurement surface

surface of a machine radiating the structure vibration generated sound where the measurement positions are

located
NOTE Its area is designated by the symbol S.
3.9
extraneous vibratory velocity level
vibratory velocity level, caused by all sources other than the source under test

NOTE Extraneous vibratory velocity levels originate, for example, from coupled assemblies.

4 Principle

4.1 The A-weighted airborne sound power radiated by a machine or equipment caused by structure

vibrations of its outer surface only, P , is generally determined by Equation (6) [see also Equation (4)]

PZ= vS ε (6)
AcA A
3)

For the purpose of this part of ISO/TS 7849, the A-weighted radiation factor ε = 1 , and for Z the

A c
normalized characteristic impedance Z = 411 N s/m is used.
c,n

NOTE The normalized characteristic impedance Z = 411 N s/m is used in accordance with the basic International

c,n
[2]

Standards for which ISO 3740 gives usage guidelines, and corresponds to meteorological conditions for atmospheric

temperature, θ = 23,0 °C, and barometric pressure, B = 1,013 × 10 Pa.
0 0
These assumptions yield the upper limit of the A-weighted airborne sound power
PZ= vS (7)
A,max c,n A

which forms the basis for the method described in this part of ISO/TS 7849, requiring only v and S to be

determined.

4.2 The value of v is obtained from measurements of the A-weighted r.m.s. vibratory velocity component

perpendicular to the outer surface of the machine and taken for a sufficient number of measurement positions

distributed over its relevant outer surface. The array and number of measurement positions can be regarded

as sufficient if the value of v remains stable within the precision of the method for an increasing number and

changed array of measurement positions.

It may be desirable to subdivide the surface area of the machine in order to rank the sound power radiated

from different components. The implication of this subdivision is that each area radiates sound independently.

The spatial variation of vibration velocity depends on

a) the number of resonant modes excited simultaneously in the frequency band of interest;

b) the degree of non-uniformity of the structure (e.g. stiffness and inertia variation);

c) the spatial distribution of the exciting forces.

3) Under certain specific conditions, values ε > 1 are possible, but they seldom occur in the practice of machinery noise

radiation. However, it may be assumed that, within the measurement uncertainty to be expected, the upper limit of the

A-weighted sound power level determined in accordance with this part of ISO/TS 7849 also covers deviations caused by

radiation factors larger than 1.
4 © ISO 2009 – All rights reserved
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SIST-TS CEN ISO/TS 7849-1:2022
ISO/TS 7849-1:2009(E)

A major problem occurs when only a very few modes are excited within a frequency band of interest.

4.3 The area of the relevant outer surface of the machine, S, can be calculated easily if the shape of the

outer surface of the machine is simple (e.g. cylindrical, spherical or composition of flat plates).

One problem is the radiation from connected structures, such as pipes, mounts, and supports, and the

radiation from the framework, rib surfaces, perforated surfaces, and supporting structures.

It is recommended that S be defined for specific kinds of machinery.
5 Measuring instrumentation
5.1 General

Measuring instrumentation using vibration transducers and other non-contacting equipment is described here.

For contacting accelerometers, it is convenient to make use of low mass-loading accelerometers, keeping in

mind the frequency range of interest. However, for special purposes, other kinds of equipment and

measurement techniques may be needed, e.g. non-contact devices and laser-Doppler methods (see Annex A).

5.2 Vibration transducer
The vibration transducer usually loads the vibrating surface.
For vibration
...

SLOVENSKI STANDARD
kSIST-TS FprCEN ISO/TS 7849-1:2021
01-december-2021
Akustika - Določanje ravni zvočnih moči v zraku, ki jih povzročajo stroji, z
merjenjem vibracij - 1. del: Informativna metoda s fiksnim faktorjem sevanja
(ISO/TS 7849-1:2009)

Acoustics - Determination of airborne sound power levels emitted by machinery using

vibration measurement - Part 1: Survey method using a fixed radiation factor (ISO/TS

7849-1:2009)

Akustik - Bestimmung der von Maschinen abgestrahlten Luftschallleistungspegel durch

Schwingungsmessung - Teil 1: Verfahren der Genauigkeitsklasse 3 mit festem
Strahlungsfaktor (ISO/TS 7849-1:2009)

Acoustique - Détermination des niveaux de puissance acoustique aériens émis par les

machines par mesurage des vibrations - Partie 1: Méthode de contrôle employant un

facteur de rayonnement fixe (ISO/TS 7849-1:2009)
Ta slovenski standard je istoveten z: FprCEN ISO/TS 7849-1
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
17.160 Vibracije, meritve udarcev in Vibrations, shock and
vibracij vibration measurements
kSIST-TS FprCEN ISO/TS 7849-1:2021 en,fr,de

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

---------------------- Page: 1 ----------------------
kSIST-TS FprCEN ISO/TS 7849-1:2021
---------------------- Page: 2 ----------------------
kSIST-TS FprCEN ISO/TS 7849-1:2021
TECHNICAL ISO/TS
SPECIFICATION 7849-1
First edition
2009-03-15
Acoustics — Determination of airborne
sound power levels emitted by machinery
using vibration measurement —
Part 1:
Survey method using a fixed radiation
factor
Acoustique — Détermination des niveaux de puissance acoustique
aériens émis par les machines par mesurage des vibrations —
Partie 1: Méthode de contrôle employant un facteur de rayonnement
fixe
Reference number
ISO/TS 7849-1:2009(E)
ISO 2009
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kSIST-TS FprCEN ISO/TS 7849-1:2021
ISO/TS 7849-1:2009(E)
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ii © ISO 2009 – All rights reserved
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ISO/TS 7849-1:2009(E)
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................................................................................................................ 5

5.4 Amplifier ................................................................................................................................................ 6

5.5 Integrator ............................................................................................................................................... 6

5.6 Calibration ............................................................................................................................................. 6

6 Installation and operation of source under test ................................................................................ 6

6.1 General................................................................................................................................................... 6

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 .......................................................................................................... 7

7.3 Number of measurement positions .................................................................................................... 8

7.4 Environmental conditions.................................................................................................................... 8

7.5 Measurement procedure ...................................................................................................................... 9

7.6 Mounting of the vibration transducer................................................................................................. 9

8 Calculations........................................................................................................................................... 9

8.1 Correction for extraneous vibratory velocity..................................................................................... 9

8.2 Determination of the mean A-weighted vibratory velocity level on the vibrating

measurement surface......................................................................................................................... 10

8.3 Calculation of the upper limit of the A-weighted airborne sound power level caused by

radiation of structure vibration generated sound ........................................................................... 11

9 Measurement uncertainty .................................................................................................................. 11

10 Information to be recorded ................................................................................................................ 13

10.1 Machine under test ............................................................................................................................. 13

10.2 Measurement conditions ................................................................................................................... 13

10.3 Measuring instrumentation................................................................................................................ 13

10.4 Acoustical data ................................................................................................................................... 13

Annex A (informative) Use of the vibration transducer................................................................................ 14

Annex B (informative) Guidance on the development of information on measurement uncertainty...... 16

Bibliography ..................................................................................................................................................... 19

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ISO/TS 7849-1:2009(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

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International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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

of the parent committee casting a vote;

⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical

committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting

a vote.

An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a

further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is

confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an

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 7849-1 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.

This first edition of ISO/TS 7849-1, together with ISO/TS 7849-2, 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
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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.

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;
[12]

⎯ 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 machine.

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 A-weighted 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 in principle. For this part of

ISO/TS 7849 a radiation factor of 1 is assumed allowing the determination of an upper limit for the radiated

A-weighted sound power level. For typical machines this upper limit may exceed the true A-weighted sound

[12]

power level determined by the intensity procedure of ISO 9614 (all parts) by up to 10 dB. The A-weighted

sound power level determined according to this part of ISO/TS 7849 can be used for sound power level

comparison of relevant vibrating machinery noise of the same family with similar design.

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kSIST-TS FprCEN ISO/TS 7849-1:2021
TECHNICAL SPECIFICATION ISO/TS 7849-1:2009(E)
Acoustics — Determination of airborne sound power levels
emitted by machinery using vibration measurement —
Part 1:
Survey method using a fixed radiation factor
1 Scope

This part of ISO/TS 7849 gives basic requirements for reproducible methods for the determination of an upper

limit for the A-weighted sound power level of the noise emitted by machinery or equipment by using surface

vibration measurements. 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] [12]

measurements, e.g. as specified in ISO 3746 , ISO 3747 , and ISO 9614 (all parts) , are not possible

because of high background noise or other parasitic environmental interferences; or if a distinction is required

between the total radiated sound power and its structure vibration generated component.

NOTE 1 One of the applications of this part of ISO/TS 7849 is the distinction between the radiation of airborne sound

power generated by structure vibration and the aerodynamic sound power components. Such a distinction is not feasible

[7] [12]
with ISO 3746 and ISO 9614 (all parts) .

NOTE 2 Problems can occur if the noise is generated by small parts of machinery surfaces (sliding contacts, e.g. slip

ring brush or the commutator and the brush in electrical machines).

The methods described in this part of ISO/TS 7849 apply mainly to processes that are stationary with respect

to time.
2 Normative references

The following referenced documents are indispensable for the application 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 5348, Mechanical vibration and shock — Mechanical mounting of accelerometers

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

measurement (GUM:1995)
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
structure vibration generated sound
airborne sound caused by structure vibration in the audible frequency range

NOTE For the purposes of this part of ISO/TS 7849, structure vibration generated sound is determined either from

the vibratory velocity or the vibratory acceleration of the surface of the solid structure.

3.2
machine

〈airborne sound power level measurement〉 equipment which incorporates a single or several noise sources

3.3
vibratory velocity

root-mean square (r.m.s.) value of the component of the velocity of a vibrating surface in the direction normal

to the surface

NOTE 1 The vibratory velocity, v, is the time integral of the vibratory acceleration, whose r.m.s. value is given for

sinusoidal vibration by:
v = (1)
2πf
where
a is the r.m.s. acceleration;
f is the frequency.

The vibratory velocity, v, is the time derivative of the vibratory displacement, s, ds/dt. For sinusoidal vibration, the r.m.s.

velocity, v, is given by:
vf=π2s (2)
where s is the r.m.s. displacement.

NOTE 2 In this part of ISO/TS 7849, the vibratory velocity is usually applied with A-weighting, denoted v .

3.4
A-weighted vibratory velocity level

ten times the logarithm to the base 10 of the ratio of the square of the r.m.s. value of the A-weighted vibratory

velocity, v , to the square of a reference value, v , expressed in decibels:
A 0
L = 10 lg dB (3)
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where

v is the A-weighted r.m.s. value of the vibratory velocity, in metres per second ;

–8 2)
v is the reference value for the velocity and is equal to 5 × 10 m/s .

NOTE For airborne and structure vibration generated sound, the reference value, v = 50 nm/s has the property that it

−5 −12 2

leads, together with p = 2 × 10 Pa, to the reference value of the intensity level I = 1 × 10 W/m and to the

0 0
characteristic impedance of air by p /v = 400 N s/m .
0 0
3.5
A-weighted radiation factor
factor expressing the efficiency of sound radiation given by:
ε = (4)
Z Sv
where

P is the A-weighted airborne sound power emitted by the vibrating surface of the machine,

[12]
determined according to ISO 9614 (all parts) ;

S is the area of the defined outer surface of the machine under test (vibrating measurement surface;

see 3.8);

v is the squared A-weighted r.m.s. value of the vibratory velocity averaged over S;

Z is the characteristic impedance of air.

NOTE The four quantities ε , P , v , and Z relate to the same period of time and to the same meteorological

A A c
conditions (atmospheric temperature, θ, and barometric pressure, B).
3.6
A-weighted airborne sound power level

ten times the logarithm to the base 10 of the ratio of the A-weighted airborne sound power emitted by the

surface of a machine, P , to a reference value, P , expressed in decibels
A 0
L = 10 lg dB (5)
W A
–12
where the reference value, P , is 10 W
3.7
upper limit of A-weighted airborne sound power level
WA,max

A-weighted airborne sound power level determined in accordance with the method described in this part of

ISO/TS 7849

1) A subscript “eff” is dropped, since only r.m.s. values are used throughout this part of ISO/TS 7849.

[1] −9 −8

2) In ISO 1683 , two reference values for the velocity level are mentioned: v = 10 m/s and 5 × 10 m/s. The latter is

intended for cases of airborne and structure vibration generated sound and is therefore used in this part of ISO/TS 7849. A

choice of v = 10 m/s results in a vibratory velocity level which is 34 dB higher than the level used in this part of

ISO/TS 7849. Therefore, if v = 10 m/s is used, subtract 34 dB from the right-hand sides of Equations (7), (8),

and (11).
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3.8
vibrating measurement surface

surface of a machine radiating the structure vibration generated sound where the measurement positions are

located
NOTE Its area is designated by the symbol S.
3.9
extraneous vibratory velocity level
vibratory velocity level, caused by all sources other than the source under test

NOTE Extraneous vibratory velocity levels originate, for example, from coupled assemblies.

4 Principle

4.1 The A-weighted airborne sound power radiated by a machine or equipment caused by structure

vibrations of its outer surface only, P , is generally determined by Equation (6) [see also Equation (4)]

PZ= vS ε (6)
AcA A
3)

For the purpose of this part of ISO/TS 7849, the A-weighted radiation factor ε = 1 , and for Z the

A c
normalized characteristic impedance Z = 411 N s/m is used.
c,n

NOTE The normalized characteristic impedance Z = 411 N s/m is used in accordance with the basic International

c,n
[2]

Standards for which ISO 3740 gives usage guidelines, and corresponds to meteorological conditions for atmospheric

temperature, θ = 23,0 °C, and barometric pressure, B = 1,013 × 10 Pa.
0 0
These assumptions yield the upper limit of the A-weighted airborne sound power
PZ= vS (7)
A,max c,n A

which forms the basis for the method described in this part of ISO/TS 7849, requiring only v and S to be

determined.

4.2 The value of v is obtained from measurements of the A-weighted r.m.s. vibratory velocity component

perpendicular to the outer surface of the machine and taken for a sufficient number of measurement positions

distributed over its relevant outer surface. The array and number of measurement positions can be regarded

as sufficient if the value of v remains stable within the precision of the method for an increasing number and

changed array of measurement positions.

It may be desirable to subdivide the surface area of the machine in order to rank the sound power radiated

from different components. The implication of this subdivision is that each area radiates sound independently.

The spatial variation of vibration velocity depends on

a) the number of resonant modes excited simultaneously in the frequency band of interest;

b) the degree of non-uniformity of the structure (e.g. stiffness and inertia variation);

c) the spatial distribution of the exciting forces.

3) Under certain specific conditions, values ε > 1 are possible, but they seldom occur in the practice of machinery noise

radiation. However, it may be assumed that, within the measurement uncertainty to be expected, the upper limit of the

A-weighted sound power level determined in accordance with this part of ISO/TS 7849 also covers deviations caused by

radiation factors larger than 1.
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A major problem occurs when only a very few modes are excited within a frequency band of interest.

4.3 The area of the relevant outer surface of the machine, S, can be calculated easily if the shape of the

outer surface of the machine is simple (e.g. cylindrical, spherical or composition of flat plates).

One problem is the radiation from connected structures, such as pipes, mounts, and supports, and the

radiation from the framework, rib surfaces, perforated surfaces, and supporting structures.

It is recommended that S be defined for specific kinds of machinery.
5 Measuring instrumentation
5.1 General

Measuring instrumentation using vibration transducers and other non-contacting equipment is described here.

For contacting accelerometers, it is convenient to make use of low mass-loading accelerometers, keeping in

mind the frequency range of interest. However, for special purposes, other kinds of equipment and

measurement techniques may be needed, e.g. non-contact devices and laser-Doppler methods (see Annex A).

5.2 Vibration transducer
The vibration transducer usually loads the vibrating surface.

For vibration measurements covering a wide frequency range, piezoelectric accelerometers are preferred.

When selecting an accelerometer for a particular application, allowance should be made for the parameters of

the transducer and the environmental conditions in which it is to be used.

Measurements are normally limited to the flat portion of the frequency response of the accelerometer, which is

limited by the resonance of the transducer at the high frequency end. As a rule of thumb, the upper frequency

limit for the measurements can be set to one-third of the resonance frequency of the accelerometer so that

vibration components measured at this limit are not affected by more than 1 dB compared with those at lower

frequencies.

Small, low-mass accelerometers may have high resonance frequencies but, in general, they have low

sensitivity (dynamic range). Therefore, a compromise has to be made because high sensitivity normally

entails a large piezoelectric assembly and, consequently, a relatively large, heavy unit with low resonance

frequency.

The mass of the accelerometer becomes important when measuring low-mass test objects for the highest

frequency of interest (see Annex A).
5.3 Non-contacting transducers

There are several transducers available for a non-contacting vibration measurement: capacitive transducers,

eddy current transducers, and magnetic transducers. Holographic methods, laser triangulation sensors and

laser Doppler vibrometers may also be used.

The transfer coefficient of capacitive transducers is inversely proportional to the distance between the

transducer and the vibrating surface. Therefore, when using a capacitive transducer, a very fine geometric

model of the surface of the structure vibration generating sound source is required, as well as an exact

positioning system in order to keep the required (small) measurement distance. The same applies for

magnetic transducers; furthermore, the transfer coefficient depends on the permeability of the outer surface.

When using laser holographic methods, the vibration data can be determined for a mesh of the whole surface

in one shot, but for each point of the mesh only one magnitude and phase value can be received. Although

necessary for sound radiation calculations, no spectral resolution of an operational deflection shape is

possible with holography.
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Laser Doppler vibrometers determine the vibration displacement with a resolution of the order of nanometres.

The distance between transducer and vibrating surface can be chosen within a wide range (usually using

focusing optics) and has no influence on the measured value. Since a laser Doppler vibrometer determines

the time signal of the vibration, a fast Fourier transform analysis can be performed.

In summary, among the methods considered, the use of a laser Doppler vibrometer is particularly

recommended for non-contacting vibration measurements on surfaces of machines or equipment.

5.4 Amplifier

Amplify the signals generated by the vibration transducer and indicate them as r.m.s. values. Measure

structure vibration generated noise with a sound level meter or an equivalent measurement system complying

with the relevant requirements of IEC 61672-1, Class 2, with the microphone replaced by the vibration

transducer.
5.5 Integrator

If an integrator to transform acceleration signals to velocity signals is used, it shall have characteristics which

match the dynamic range of the measuring system. If this requirement is not satisfied and the signal to be

measured is too low, calculate the vibratory velocity levels directly from the vibratory acceleration levels.

5.6 Calibration
[13]

Information on the calibration of vibration and shock transducers is given in ISO 16063 (all parts) .

If the vibration transducer is calibrated by a sinusoidal acceleration signal, the resulting A-weighted vibratory

velocity level, L , in decibels, is given by:
L = 20 lg dB (8)
...

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