prEN ISO 3382-3

Acoustics - Measurement of room acoustic parameters - Part 3: Open plan offices (ISO/DIS 3382-3:2021)

Akustik - Messung von Parametern der Raumakustik - Teil 3: Großraumbüros (ISO/DIS 3382-3:2021)

Dieses Dokument legt Verfahren zur Messung von Parametern der Raumakustik in unbesetzten Großraumbüros fest. Festgelegt werden Messverfahren, die benötigte Prüfeinrichtung, die erforderliche Messpunktdichte, das Verfahren zur Bewertung der Daten und die Angabe des Prüfberichts.

Acoustique - Mesurage des paramètres acoustiques des salles - Partie 3: Bureaux ouverts (ISO/DIS 3382-3:2021)

Akustika - Merjenje parametrov prostorske akustike - 3. del: Velike odprte pisarne (ISO/DIS 3382-3:2021)

General Information

• Status: Not Published
• ICS: 91.120.20 - Acoustics in building. Sound insulation
• Technical Committee: CEN/TC 126 - Acoustic properties of building products and of buildings
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Due Date: 12-Aug-2021
• Completion Date: 12-Aug-2021
• Ref Project: oSIST prEN ISO 3382-3:2021 - Acoustics - Measurement of room acoustic parameters - Part 3: Open plan offices (ISO/DIS 3382-3:2021)

RELATIONS

• Revised: EN ISO 3382-3:2012 - Acoustics - Measurement of room acoustic parameters - Part 3: Open plan offices (ISO 3382-3:2012)
• Effective Date: 19-Dec-2018

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 3382-3:2021
01-marec-2021

Akustika - Merjenje parametrov prostorske akustike - 3. del: Velike odprte pisarne

(ISO/DIS 3382-3:2021)
Acoustics - Measurement of room acoustic parameters - Part 3: Open plan offices
(ISO/DIS 3382-3:2021)

Akustik - Messung von Parametern der Raumakustik - Teil 3: Großraumbüros (ISO/DIS

3382-3:2021)
Acoustique - Mesurage des paramètres acoustiques des salles - Partie 3: Bureaux
ouverts (ISO/DIS 3382-3:2021)
Ta slovenski standard je istoveten z: prEN ISO 3382-3
ICS:
17.140.01 Akustična merjenja in Acoustic measurements and
blaženje hrupa na splošno noise abatement in general
91.120.20 Akustika v stavbah. Zvočna Acoustics in building. Sound
izolacija insulation
oSIST prEN ISO 3382-3:2021 en,fr,de

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

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oSIST prEN ISO 3382-3:2021
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oSIST prEN ISO 3382-3:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 3382-3
ISO/TC 43/SC 2 Secretariat: DIN
Voting begins on: Voting terminates on:
2021-01-29 2021-04-23
Acoustics — Measurement of room acoustic parameters —
Part 3:
Open plan offices
Acoustique — Mesurage des paramètres acoustiques des salles —
Partie 3: Bureaux ouverts
ICS: 91.120.20
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 3382-3:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
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oSIST prEN ISO 3382-3:2021
ISO/DIS 3382-3:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

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Published in Switzerland
ii © ISO 2021 – All rights reserved
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oSIST prEN ISO 3382-3:2021
ISO/DIS 3382-3:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 Measurement conditions ............................................................................................................................................................................. 3

4.1 Equipment ................................................................................................................................................................................................... 3

4.2 Measurement procedure ................................................................................................................................................................ 3

4.2.1 Measurement conditions .......................................................................................................................................... 3

4.2.2 Room acoustic zones .................................................................................................................................................... 3

4.2.3 Source and microphone positions .................................................................................................................... 4

4.2.4 Measurement quantities ........................................................................................................................................... 5

5 Determination of single-number quantities ........................................................................................................................... 6

5.1 Spectrum of normal speech ......................................................................................................................................................... 6

5.2 Spatial decay rate of speech ......................................................................................................................................................... 6

5.2.1 Conventional method ................................................................................................................................................... 6

5.2.2 Impulse response method ....................................................................................................................................... 8

5.3 Speech level at 4 m distance ........................................................................................................................................................ 8

5.4 Background noise ................................................................................................................................................................................. 9

5.5 Speech Transmission Index ......................................................................................................................................................... 9

5.6 Comfort and distraction distances ......................................................................................................................................10

5.7 Typical values of single-number quantities ................................................................................................................11

6 Precision ....................................................................................................................................................................................................................11

7 Test report ................................................................................................................................................................................................................11

Annex A (informative) Psychological reasoning of distraction distance .....................................................................13

Annex B (informative) Alternative methods for determining the spatial decay rate .....................................14

Annex C (informative) Examples of typical values of the single-number quantities .......................................16

Annex D (informative) Accuracy ............................................................................................................................................................................17

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

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Foreword

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

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

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

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

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

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

electrotechnical standardization.

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

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

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

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

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

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

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

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

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

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee [or Project Committee] ISO/TC 43, Acoustics,

Subcommittee SC 2, Building acoustics.

This second edition cancels and replaces the first edition (ISO 3382-3:2012), which has been technically

revised. The main changes compared to the previous edition are as follows:

— new single-number quantity, comfort distance, added, and privacy distance removed;

— use of omnidirectional sound source emphasized;
— measurement conditions (Clause 4) have been clarified;
— determination of single-number quantities (Clause 5) clarified;
— use of impulse response method better described and a new Annex added;
— new Clause 6 Precision and a new informative Annex Accuracy added;

— STI is determined in conformance of IEC 20268-16 using weighting factors α and β for male gender;

A list of all parts in the ISO 3382 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
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Introduction

Noise and lack of speech privacy are among the most dissatisfactory environmental factors in open-

plan offices [1]. Colleagues’ speech is the main source of office noise. Inadequate room acoustic design

of the office is one reason to the perception of noise and lack of speech privacy. Distraction due to

colleagues’ speech weakens the ability to concentrate and reduces productivity, especially in tasks

requiring cognitive resources. Insufficient speech privacy prevents confidential conversations. Several

experimental studies suggest that distraction can be reduced by reducing speech intelligibility [2,3].

A large field survey supports that reduced speech intelligibility is associated with reduced noise

disturbance [4].

This part of ISO 3382 specifies a measurement method, which results in a group of single-number

quantities indicating the room acoustic performance of an open-plan office in a condition when one

person is speaking. They focus on spatial decay of speech while quantities in part 2 of this standard

focus on temporal decay of sound.

The concept "open-plan offices" covers large office spaces where large number of occupants can work in

well-defined workstations. A large share of flexible offices and activity-based offices belong to the open-

plan office concept of this standard. Open-plan offices can also be found in libraries, hospital wards,

industrial workplaces, and schools. According to [4], many of the single-number quantities provided by

this standard are associated with the perceived noise disturbance in open-plan offices.

Room acoustic quality can be affected by the amount and positioning of absorption materials, room

geometry, workstations, screens, other furniture, and background noise level, i.e. sound masking.

Current literature gives good advice how the room acoustics should be designed to reach good room

acoustic quality as it is defined in this standard [5,6,7].

The method describes the acoustic performance of the open-plan office in a standardized condition

where a single occupant is speaking with normal speech effort. The background noise caused by

building appliances or electronic masking sound is considered. The measurements are conducted in

an unoccupied open-plan office because the method concerns the permanent building properties and

stable room acoustic conditions as well as parts 1 and 2 of this standard. The actual noise conditions

during use of the space do not belong to the scope of this standard. Although the activity noise caused

by occupants can be significantly larger than the background noise from building appliances or sound

masking, activity noise is beyond the scope of this standard. Presentation of acoustic design guidelines

is also beyond the scope of this part of ISO 3382-3.
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oSIST prEN ISO 3382-3:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 3382-3:2021(E)
Acoustics — Measurement of room acoustic parameters —
Part 3:
Open plan offices
1 Scope

This document specifies methods for the measurement of room acoustic parameters in unoccupied

open-plan offices. It specifies measurement procedures, the apparatus needed, the coverage required,

the method for evaluating the data, and the presentation of the test report.
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 3382-1, Acoustics — Measurement of room acoustic parameters — Part 1: Performance spaces

ISO 3740, Acoustics — Determination of sound power levels of noise sources — Guidelines for the use of

basic standards

IEC 60268-16:2011, Sound system equipment — Part 16: Objective rating of speech intelligibility by speech

transmission index
IEC 60942, Electroacoustics — Sound calibrators
IEC 61260, Electroacoustics — Octave-band and fractional-octave-band filters
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
Omnidirectional sound source
OSS
a sound source which radiates sound evenly to all directions.
3.2
spatial distribution of the A-weighted SPL of speech

curve which shows how the A-weighted sound pressure level (SPL) decreases as a function of the

distance from the middle point of the OSS emitting noise with the sound power level of normal speech

within 125 Hz to 8 000 Hz.
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3.3
spatial decay rate of speech
2,S

rate of spatial decay of A-weighted SPL of speech per distance doubling in decibels

Note 1 to entry: The quantity describes how fast the A-weighted SPL of speech attenuates in the open-plan office.

Large value means strong overall room acoustic attenuation. In free field, D = 6 dB.

2,S
3.4
Speech level at 4 m distance
p,A,S,4m

nominal A-weighted SPL in decibels at the distance of 4,0 m from the middle point of the OSS emitting

noise with the sound power level of normal speech within 125 Hz to 8 000 Hz

Note 1 to entry: The quantity describes the A-weighted SPL of speech at a distance within which the nearest

workstation is nearly always located. Small value means strong room acoustic attenuation near the OSS.

3.5
comfort distance

distance from the speaker in meters where the A-weighted SPL of speech falls below 45 dB when the

OSS is emitting noise with the sound power level of normal speech within 125 Hz to 8 000 Hz

Note 1 to entry: Comfort distance reduces with increasing D2,S and decreasing Lp,A,S,4m.

3.6
background noise level
p,B

unweighted mean SPL of background noise in decibels present at the workstations along the

measurement path during working hours when occupants are absent

Note 1 to entry: Background noise is measured in octave bands within 125 Hz to 8 000 Hz.

3.7
speech transmission index
STI

a proportional number representing the transmission quality of speech. STI has a value between 0.00

and 1.00.
[SOURCE: IEC 60268-16:2011]

Note 1 to entry: The value of STI is associated with subjective speech intelligibility.

3.8
spatial distribution of the speech transmission index

curve which shows how the STI decreases as a function of the distance from the OSS.

3.9
distraction distance
distance from the OSS in meters where the STI falls below 0,50.

Note 1 to entry: to entry. Distraction distance reduces with decreasing r and increasing L . Small value

C p,B

indicates high speech privacy. When the speaker is located beyond the distraction distance from the occupant,

occupant’s work performance is expected to be better than at shorter distances (see Annex A).

3.10
Workstation

Workstation is a furniture ensemble containing one ergonomically adjustable chair and a working table

having a minimum floor area of 70x70 cm. The height of tabletop can be adjusted to a height of 75

cm from the floor. Workstation can contain also other components, such as screen(s), storage unit(s),

display units, or luminaire.
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4 Measurement conditions
4.1 Equipment

4.1.1 Sound source. Omnidirectional sound source (abbreviated by OSS) shall be used in all

measurements. This source type is used since occupants in an open-plan office do not speak in an exactly

fixed direction. The requirements given in ISO 3382-1 for the OSS within 125 – 4000 Hz shall be fulfilled

for measurements to be in accordance with this part of ISO 3382.
NOTE There are no requirements for the 8 000 Hz octave band.

4.1.2 Microphone. SPLs in each octave band and at each microphone position shall be measured

using a sound level meter meeting the requirements of IEC 61672-1, class 1. The microphone shall be

omnidirectional considering any supplementary equipment connected to it.

4.1.3 Analyzer. The octave-band filters of the analyzer or analyzer software shall comply with

IEC 61260. If the signal is recorded, e.g., by using analogue or digital recorders for off-line processing, it

shall be ensured that the whole instrumentation complies with the above-mentioned requirements.

4.1.4 Calibrator. Before and after each measurement series, the acoustical sensitivity of the

measurement system shall be checked using a sound calibrator that complies with IEC 60942. The results

of the calibration checks shall be documented. A difference of more than 0,5 dB between calibration

checks shall be a cause to repeat measurements. It is recommended that the calibration be checked

whenever batteries or open-plan office are changed.
4.2 Measurement procedure
4.2.1 Measurement conditions

Measurements can be conducted in open-plan offices of any kind and with any configuration of ceiling

absorbers, wall absorbers, sound masking systems, floor coverings, fixed partitions, workstations,

screens, storage units, and other furniture, whether they are fixed or mobile. The results are valid only

to the specified configuration which prevails during the measurement. Therefore, it is important to

carefully report these factors along with the measurement results.

Background noise means all stationary sounds, which are present during normal working hours

and are not caused by the occupants. Such sounds are e.g. heating, ventilation, and air conditioning

(HVAC) devices, environmental noise caused by sources outside the building, or an electronic sound-

masking system.

The HVAC devices shall operate on the same power as during typical working hours. If the office is

equipped with a sound-masking system, it shall be switched on during the measurement. Sound

masking shall operate at the same level and with the same spectrum as during typical working hours.

Adaptive masking systems should be tested separately for minimum and maximum levels. Appliances

such as refrigerators, printers, coffee machines, radios, and video projectors shall be shut down if they

increase the background noise in any measurement position. Windows and balcony doors shall be

closed. All measurements shall be conducted when the occupants are absent. Only the measurement

technician can be present in the open-plan office.

If the table heights are electrically adjustable, the tabletop height is set to 75±5 cm from the floor in the

workstations located along the measurement path.
4.2.2 Room acoustic zones

If the open-plan offices can contain two or more zones where the absorption treatments and/or

furniture layouts are different, the measurements shall be conducted in each zone and the reported

single-number quantities are determined for each zone separately.
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At least two separate measurement paths shall be used per open-plan office zone. If only one

measurement path is possible, measurements shall be conducted in both directions along the same

measurement path.
4.2.3 Source and microphone positions

The measurements shall be conducted along a straightest possible path which crosses over

workstations, as shown in Figure 1.

If the zone contains regular furniture (usually screen or storage unit) between workstations, the

measurement path should be chosen in such a way that there is an obstacle between the OSS and the

first measurement position.

The OSS is located at the workstation at one end of the path. The OSS shall be located at the position of

a sitting occupant’s head in a workstation. The middle point of the OSS shall be at the height of 1,2 m

above the floor. The position of the OSS shall be at least 0,4 m from the nearest table and at least 1,0 m

from walls and other reflecting surfaces.

All workstations shall be measured along the measurement path and considered in the analysis. The

number of measurement positions on a path shall be at least 4. In other words, measurements according

to this standard are only possible if measurement path involves at least five consecutive workstations.

The preferred number of successive measurement positions on the path is 6 to 10.

The reference position shall be located at the distance of 1,0 m from the middle point of the OSS without

any separating obstacles, such as a screen, between the OSS and the microphone. The reference position

needs not to locate in the direction of the measurement path if an obstacle prevents the abovementioned

condition. The reference position enables a post check of the actual sound power level of the OSS.

Although the position is not utilized in the determination of the single-number quantities, the result

can be shown in spatial decay curves of both A-weighted SPL of speech and STI to provide additional

information about the acoustic conditions at short conversation distance.

The actual measurement positions, which affect the reported single-number quantities, shall locate in

workstations along the measurement path at the position of a sitting occupant’s head at the height of

1,2 m above the floor. The second measurement position shall locate in the workstation nearest to the

OSS. Standing occupants are not considered in this part of ISO 3382. The position of microphone shall

be at least 0,4 m from tables and at least 1,0 m from walls and other reflecting surfaces.

Even if electric tables enable working in standing position, both OSS and microphones shall be installed

at a height of 1.20 m height from the floor.
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Key
A straight measurement path
B non-straight measurement path

Figure 1 — Example of a straight and a non-straight measurement path in an open-plan office,

where workstations and other furniture are present. Position of the OSS is in the end of a path.

If the measurements are conducted in an open-plan office where the workstations and other furniture

have not yet been installed, the number of measurement positions and positions of both OSS and

microphone shall the same as above. The measurement positions shall be chosen using typical mutual

workstation distances. The measurement positions could be located, e.g., at distances 1,0 m, 2,5 m,

5,0 m, 7,5 m, 10,0 m, 12,5 m, 15,0 m, and 17,5 m from the OSS.
4.2.4 Measurement quantities
At every measurement position, four measurements or determinations are made:
— distance to the OSS disregarding the obstacles, r;
— unweighted SPL of wide-band noise caused by the OSS, L ;
p,oss
— unweighted SPL of background noise, L ;
p,B
— STI;

The accuracy of distance measurement shall be less than 0,10 m. Distances should be based on physical

measurements on site. A laser distance meter is preferred. If the distance cannot be measured due to

e.g. obstacles on measurement path, and the distances must be based on layout drawings, the accuracy

of these drawings (open-plan office dimensions, furniture positions) shall be confirmed by physical

measurements on site.

The distance means the straight distance from the midpoint of the OSS to the midpoint of the

microphone.
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L and L are measured in octave bands within 125 Hz to 8 000 Hz. The integration time shall be at

p,oss p,B
least 10 s.

NOTE Integration times longer than 10 s are needed for transient background noise, e.g. traffic noise.

5 Determination of single-number quantities
5.1 Spectrum of normal speech

The sound power level (SWL) of normal effort speech is used. The octave band values represent normal

effort unisex speech (average of female and male speech). The octave band SPL at a distance of 1,0 m

from the middle point of the OSS in the free field (L ) is presented in Table 1. The SWL of normal

p,S,1m,ff

effort speech is related to the SPL of speech at the distance of 1,0 m in free field by L = L + 11 dB.

W,S p,S,1m,ff

Since the OSS is used in all measurements, the SPL at the distance of 1,0 m from the OSS represent the

average sound radiation in all directions from the OSS.

Table 1 — The unweighted SPL of directional and omnidirectional speech at a distance of 1,0 m

from the speaker in free field and the corresponding SWL of speech. A-weighting is needed in

formula (5).
Band No. Frequency SPL of speech SPL of speech SWL of speech A-weighting
directional omnidirectional
i f L L L A
p,S,1m,ff p,S,1m,ff W,S
Hz dB re 20 μPa dB re 20 μPa dB re 1 pW dB
1 125 51,2 49,9 60,9 -16,1
2 250 57,2 54,3 65,3 -8,6
3 500 59,8 58,0 69,0 -3,2
4 1 000 53,5 52,0 63,0 0,0
5 2 000 48,8 44,8 55,8 1,2
6 4 000 43,8 38,8 49,8 1,0
7 8 000 38,6 33,5 44,5 -1,1
A-weighted 59,5 57,4 68,4

NOTE The SPL of directional speech within 250–8000 Hz is based on ANSI S3.5 [8]. The value at 125 Hz has

been chosen to be 6 dB under the SPL at 250 Hz. The SPL of omnidirectional speech is derived in [9] assuming the

directivity pattern of speech reported in [10]. Both directional and omnidirectional sources produce the same SWL.

5.2 Spatial decay rate of speech
5.2.1 Conventional method

Conventional method is based on the measurements of SPL produced by a calibrated OSS (abbreviated

by “oss” in related subindex). The SWL of the OSS producing wide-band noise shall be sufficiently high

in each octave band so that the SPL
...