ETSI ETS 300 753 ed.1 (1997-10)

SLOVENSKI STANDARD
SIST ETS 300 753 E1:2006
01-februar-2006
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Equipment Engineering (EE); Acoustic noise emitted by telecommunications equipment

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

Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the

Whilst every care has been taken in the preparation and publication of this document, errors in content,

typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to

"ETSI Editing and Committee Support Dept." at the address shown on the title page.

Foreword .......................................................................................................................................................5

Introduction....................................................................................................................................................5

1 Scope ..................................................................................................................................................7

2 Normative references..........................................................................................................................7

3 Definitions and symbols ......................................................................................................................8

3.1 Definitions ...........................................................................................................................8

3.2 Symbols ...............................................................................................................................9

4 Measurement methodology.................................................................................................................9

5 Installation and operation of equipment ..............................................................................................9

5.1 Equipment installation..........................................................................................................9

5.2 Equipment operation "in-use" ..............................................................................................9

5.2.1 Variable emissions - standard temperature test............................................10

5.2.2 Variable emissions - high temperature test...................................................10

6 Acoustic noise emission limits...........................................................................................................10

7 Information to be recorded ................................................................................................................12

8 Information to be reported.................................................................................................................12

9 Verification of declared A-weighted sound power levels...................................................................12

Annex A (normative): Measurement methods for acoustic noise emission from open air outdoor

equipment...........................................................................................................13

A.1 Scope ................................................................................................................................................13

A.2 Source directionality ..........................................................................................................................13

A.3 Installation and operation of equipment ............................................................................................13

A.3.1 Daytime simulation.............................................................................................................13

A.3.2 Night-time simulation .........................................................................................................13

A.4 Information to be recorded ................................................................................................................13

A.5 Information to be reported.................................................................................................................13

Annex B (normative): Recommended sound power limits for open air outdoor equipment..................14

Annex C (informative): Recommended method for the detection and reporting of prominent discrete

tones...................................................................................................................16

Annex D (informative): Motivation for this ETS .......................................................................................17

Annex E (informative): The relationship between sound power and sound pressure.............................18

Annex F (informative): Sound power measurement methods ................................................................19

F.1 Reverberation room technique..........................................................................................................19

F.1.1 Concept..............................................................................................................................19

F.1.2 Measurement procedure................................................................................................... 19

F.2 Free field over a reflecting plane technique...................................................................................... 19

F.2.1 Concept............................................................................................................................. 19

F.2.2 Measurement procedure................................................................................................... 20

History......................................................................................................................................................... 21

This European Telecommunication Standard (ETS) has been produced by the Equipment Engineering

(EE) Technical Committee of the European Telecommunications Standards Institute (ETSI).

Compatibility with the end-use environment is a primary concern for purchasers and manufacturers of

telecommunications equipment. An important compatibility issue is the amount of acoustic noise emitted

by the equipment. This ETS is intended to meet four primary needs of purchasers and manufacturers with

To develop practical specifications and to have the capacity to make fair comparisons between

equipment, it is essential to have a single, technically established method for the measurement of acoustic

emission. Therefore, this ETS specifies the use of sound power measurement and, more specifically,

Sound power levels can be used for direct comparison of noise emission for functionally similar equipment

manufactured by different vendors, and/or in the calculation of estimated sound pressure levels for spaces

where the equipment is to be installed. The use of sound power level, instead of emission sound pressure

level, as the specified quantity for product noise emission has clear precedent within the international

The acceptability of the acoustic emission from a piece of equipment depends upon a number of details

that vary from installation to installation, and the number of possible installations is extensive. Accordingly,

the goal of this ETS is to specify limits that are applicable to the major installation categories.

The fundamental concern prompting the development of this ETS is the potential adverse impact that

excessive equipment noise can have on people. For that reason, the impact of noise upon human

activities has been carefully considered, and the intent has been to ensure that the acoustic noise emitted

is at, or below, generally accepted levels. The perceptual issues considered included task concentration,

speech communication, annoyance and other similar parameters. Generally, the relevant noise exposure

levels are well below those needed to ensure worker safety and health. Requirements related to worker

safety and health (including those related to infrasound and ultrasound) can be found in EEC Directive

This ETS specifies that manufacturers report measured A-weighted sound power values for equipment.

Given that it is impractical and unnecessary to measure every manufactured unit, the reported sound

power value should be one that all, or nearly all, units of a particular model will not exceed. This means

that the reported value needs to take into account both production variation and the precision of the

measurement method. ISO 9296 [2] specifies methods that address these issues and is therefore

specified in this ETS as the method for declaring sound power values. ISO 9296 [2] also specifies a

For further information regarding the motivation for the development of this standard, see annex D.

This European Telecommunication Standard (ETS) specifies acoustic noise emission limits for equipment

used in telecommunication locations as specified in the ETS 300 019-1 [3] series. This ETS covers

switching, transmission, power, supervisory, as well as tariff and billing equipment.

This ETS also specifies methods for measuring, reporting and verifying the noise emission of

telecommunications equipment. The details of the methods are found in ISO 7779 [1] and ISO 9296 [2].

The descriptor used to quantify acoustic noise emission is the declared A-weighted sound power level in

The limits contained herein apply only to the airborne acoustic noise generated by equipment during

normal operation. That is, the limits do not apply when operating under emergency conditions or when the

equipment is being serviced. Also, the limits do not apply to equipment features which produce sound as

an intentional aspect of their operation, e.g. alarm signals, attention signals, speech signals and so on.

(For more information on that topic, see ETR 116 [5]). Furthermore, the present document does not

Contained within the present document are 6 annexes. Annex A specifies methods for measuring the

acoustic noise emitted from equipment manufactured for open air outdoor locations. Annex B contains

tables of recommended A-weighted sound power limits for open air outdoor equipment. Annex C

discusses the emission of pure tones from equipment. Annex D reviews the motivation for the creation of

this ETS. Annex E discusses the relationship between sound power and sound pressure. Annex F briefly

This ETS incorporates by dated or undated reference provisions from other publications. These normative

references are cited at the appropriate places in the text and the publications are listed hereafter. For

dated references, subsequent amendments to or revisions of any of these publications apply to this ETS

only when incorporated in it by amendment or revision. For undated references the latest edition of the

The following terms have the meanings as defined in ISO 7779 [1] and ISO 9296 [2], which are here

sound power level (L ): The logarithm (base 10) of the ratio of a given sound power to the reference

sound power. The weighting network (A-weighting) or the width of the frequency band used needs to be

declared A-weighted sound power level (L ): A statistical maximum A-weighted sound power level

for manufactured units, taking into account tolerances of production and measurement variance,

NOTE 1: Typically, L is 0,3 bels higher than the A-weighted sound power level measured on

sound pressure level (L ): Ten times the logarithm (base 10) of the ratio of the time-mean-square sound

pressure to the square of the reference sound pressure. The weighting network (A-weighting) or the width

of the frequency band used needs to be indicated. The reference sound pressure is 20 μPa. Units:

A-weighting filter: Response characteristic of a filter used in acoustic measurement systems which

attenuates low frequency and high frequency acoustic energy. This filter is used to provide a frequency

high temperature A-weighted sound power level (HL ): A statistical maximum A-weighted sound

power level for manufactured units, taking into account tolerances of production and measurement

variance. The method for determining the high temperature A-weighted sound power level is similar to that

used in the determination of declared sound power values, as described in ISO 9296 [2]. HL is used

high temperature limit: The maximum temperature specified for the stated environmental class of the

telecommunication equipment room: An area dedicated to large telecommunication systems.

Unattended rooms are typically occupied only for service and maintenance activities. These activities may

business area: An area where the principal activity is office / clerical work or similar activities. These

areas typically contain multiple single-person work areas. Sound levels should be low enough to provide

office: An area where individuals are primarily engaged in individual or small group intellectual tasks

which require excellent conditions for task concentration and speech communication. A typical example

power room: Defined as an area designed to house heavy equipment including, but not limited to, power

generation equipment, heating equipment, and ventilation equipment. Typically occupied only for short

underground vault: Defined as a sealed underground enclosure which is large enough to be entered for

servicing equipment contained therein. Typically occupied only for service and maintenance activities.

protected area: Location intended to be used for rest, recuperation and contemplation.

NOTE 2: There is no IEC description for this class but there is a requirement of some European

rural: Relating to areas, typically, in the countryside with low population density.

urban: Relating to areas, typically, in towns and cities with high population density.

industrial: Relating to areas, typically, of transient population and heavy manufacturing activity.

daytime: The part of the day considered to extend over normal waking hours. Typically, the period during

which people are most likely to be engaged in activities related to business, education, active recreation,

night-time: The part of the day considered to be normal sleeping hours. This period includes evening and

early morning hours when people are likely to be awake but not yet fully involved in typical daytime

The measurement methods specified in ISO 7779 [1] shall be used for determining the sound power of

products. Annex A contains additional methods and measurements relating to open air outdoor

The installation and operation conditions specified in ISO 7779 [1] shall be used for determining the sound

power of products. Where there are differences between this ETS and ISO 7779 [1], the requirements

The equipment shall be configured and operated according to its normal intended use. Within that

constraint and the constraints specified below, the equipment shall be configured and operated to ensure

The specific installation will depend upon the sound power measurement technique being used

(reverberation room or free-field over a reflecting plane), and upon the normal installation requirements of

For telecommunication equipment whose operational noise varies with functional load, the electrical input

and load conditions of the equipment shall be chosen to obtain full functional utilization of the equipment

under test. Dissipation shall be maximized by selection of supply power and load conditions.

Only the sound power of continuous, steady-state noise sources shall be measured. Therefore, the

equipment is to be operated such that intermittent sources are not active. Such sources include (but are

not restricted to) alarms, attention signals, printing mechanisms, disk-drive seeking mechanisms and so

For telecommunication equipment whose operational noise varies with temperature (e.g. equipment using

variable speed air moving devices), the sound power will be measured with the equipment operating

For the first test, the ambient temperature in the test environment shall be 23°C ± 2°C, in accordance with

ISO 7779 [1]. Data obtained from testing as specified in this clause is to be used in the determination of

For the second test, the sound power shall be measured with the equipment operating as it would in an

ambient temperature equal to the high temperature limit (see next paragraph). Data obtained from testing

as specified in this clause is to be used in the determination of the high temperature A-weighted sound

This requirement can be satisfied using one of two methods. In the first method, the ambient temperature

in the test environment shall be the high temperature limit. In the second method, the ambient

temperature in the test environment shall be 23°C ± 2°C but, the rotational speed of air moving devices

within the equipment under test shall be set to the speed that the devices would run at when the

equipment is operating in an ambient temperature equal to the high temperature limit.

Maximum acoustic noise emission levels for telecommunication equipment are specified in tables 1 to 4.

Entries are organized according to the Environmental Classes specified in ETS 300 019-1 [3] and to the

environmental descriptions found in subclause 3.1 of the present ETS. In accordance with ISO 9296 [2],

these maximum product emission levels are declared A-weighted sound power levels, L , in units of

bels. As specified in clause 8, manufacturers are to provide declared A-weighted sound power levels for

their products. Consequently, the data provided by manufacturers can be compared directly to the values

in tables 1 to 4. In order to avoid possible conflict with noise exposure regulations that exist within some

European countries, open air outdoor equipment noise emission is not addressed here but is discussed in

The limits apply only to L values, and are not applicable to HL values. Furthermore, the limits

Note that some environmental descriptions have sub-categories based upon typical equipment placement.

Equipment intended to be located in close proximity to desk work locations has lower acceptable limits

These limits apply to a functional unit as defined in clause 4 of ISO 7779 [1]. If a functional unit consists of

multiple frames, these limits apply to a single frame as described in subclause 5.5 of ISO 7779 [1].

NOTE 1: "nr" indicates that these table entries are not relevant to telecommunication equipment.

NOTE 2: Environmental Classes 3.4, 3.5, 4.1, 4.1E, 6.2, 6.3 and 7.3 are discussed in annex B.

1) The information to be recorded shall be as specified in ISO 7779 [1], including bystander and/or

2) For telecommunication equipment whose operational noise varies with temperature, the high

temperature A-weighted sound power level shall be recorded in bels, to the nearest 0,1 bels.

Similarly, the high temperature limit (in °C) and the test method used per subclause 5.2.2 shall be

The following information shall be given in implementation conformance statements:

1) a statement specifying which Environmental Classes (see ETS 300 019-1 [3]) and environmental

2) a statement that sound power levels have been obtained in full conformance with the procedures of

3) the declared A-weighted sound power level of the product, L . The value L shall be

determined according to the method specified in ISO 9296 [2] and using data obtained as specified

4) for equipment whose operational noise varies with temperature, the high temperature A-weighted

specified in ISO 9296 [2] and using data obtained as specified in subclause 5.2.2.

NOTE: As described in ISO 9296 [2], A-weighted sound power measurements are to be made

power level or a high temperature sound power level for the production series or a

This clause specifies a verification method for declared A-weighted sound power values, L .

The verification method specified in ISO 9296 [2] shall be used when verification of compliance with this

ETS is required. When conducting sound power measurements, the equipment shall be operated as

This annex specifies additional methods for the measurement of noise emitted by equipment designed for

open air outdoor locations. This information has been provided in a separate annex since the associated

limits (annex B) are currently only recommended values. It is anticipated that this annex will be

In accordance with the main body of this ETS, this annex requires that the declared A-weighted sound

power level, L , of relevant products be measured and recorded. Additionally, this annex specifies that

additional sound pressure measurements be performed for the purpose of providing an indication of

source directionality. All relevant clauses of the main body of the ETS shall be adhered to in conducting

the measurements, and in the recording and reporting of data. Where there are differences between this

annex and the main body of the ETS, the requirements contained herein shall be followed.

In addition to the measurement of sound power, an indication of the source directionality shall be obtained

by using only the bystander position measurement method specified in clause 7 of ISO 7779 [1]. That

clause shall be adhered to in conducting the measurements, and in the recording and reporting of