SIST EN ISO 3381:2021
(Main)Railway applications - Acoustics - Noise measurement inside railbound vehicles (ISO 3381:2021)
Railway applications - Acoustics - Noise measurement inside railbound vehicles (ISO 3381:2021)
This document specifies the measurement method and conditions to obtain reproducible noise levels on-board all kinds of vehicles operating on rails or other types of fixed track, hereinafter conventionally called “unit”, except for track maintenance vehicles in working modes.
This document is applicable to type testing. It does not include all the instructions to carry out monitoring testing or evaluation of noise exposure of passengers or drivers over a whole journey.
This document is not applicable to guided buses.
It provides measurement procedures for vehicle interior noise (in general, a vehicle type test is carried out using only a selected subset of these tests):
— when the vehicle is moving at constant speed;
— when the vehicle is stationary;
— when the vehicle is accelerating or decelerating;
— in the driver's cab when an external warning horn is sounding (specifically required for European Union regulation application)
It does not provide measurement procedures for:
— audibility or intelligibility of any audible signals;
— assessment of warning devices other than warning horns.
The assessment of noise exposure of train crew due to operational conditions is not in the scope of this document.
The results can be used, for example:
— to characterise the noise inside these units;
— to compare the internal noise of various units on a particular track section;
— to collect basic source data for units.
The test procedures specified in this document are of engineering grade (grade 2), the preferred grade for noise declaration purposes as defined in ISO 12001. If test conditions are relaxed, for example as they are for monitoring of in-service trains, then the results are no longer of engineering grade.
The procedures specified for accelerating and decelerating tests are of survey grade (grade 3).
Bahnanwendungen - Akustik - Geräuschmessungen in spurgebundenen Fahrzeugen (ISO 3381:2021)
Dieses Dokument legt das Messverfahren und die Bedingungen fest, die einzuhalten sind, um an Bord aller Arten von Schienenfahrzeugen oder anderen spurgebundenen Fahrzeugen, nachfolgend „Einheiten“ genannt, mit Ausnahme von Fahrzeugen zur Wartung des Fahrweges, reproduzierbare Geräuschpegel zu erhalten.
Dieses Dokument ist für Typprüfungen anwendbar. Es enthält nicht alle Anweisungen zur Ausführung von Überwachungsprüfungen oder zur Bewertung der Geräuschbelastung von Fahrgästen oder Fahrzeugführern über eine ganze Fahrtstrecke.
Dieses Dokument ist nicht auf spurgeführte Busse anwendbar.
Es enthält Messverfahren zur Messung des Geräusches im Fahrzeuginneren (Im Allgemeinen ist für Fahrzeugabnahmeprüfungen nur eine Auswahl dieser Prüfungen erforderlich.):
wenn sich das Fahrzeug mit konstanter Geschwindigkeit bewegt;
wenn das Fahrzeug stillsteht;
wenn das Fahrzeug beschleunigt oder abbremst;
im Führerraum, wenn ein externes Signalhorn ertönt (speziell für die Anwendung von EU-Verordnung erforderlich).
Es enthält keine Messverfahren für
die Hörbarkeit oder Verständlichkeit akustischer Signale, und
die Beurteilung von anderen Warneinrichtungen als den Signalhörnern.
Die Beurteilung der Geräuscheinwirkung auf das Zugpersonal aufgrund der Betriebsbedingungen ist nicht Gegenstand des vorliegenden Dokuments.
Die Ergebnisse können z. B. genutzt werden,
um die Geräusche im Inneren dieser Einheiten zu beschreiben,
um die Geräusche im Inneren verschiedener Einheiten auf einem bestimmten Gleisabschnitt zu vergleichen, und
um grundlegende Quelldaten für Einheiten zu erfassen.
Die in diesem Dokument festgelegten Prüfverfahren sind Verfahren der Genauigkeitsklasse 2, der bevorzugten Genauigkeitsklasse für die Zwecke der Geräuschangabe, wie in ISO 12001 festgelegt. Falls Prüfbedingungen gelockert werden, wie z. B. bei der Überwachung von Zügen während des Betriebs, entsprechen die Ergebnisse nicht mehr der Genauigkeitsklasse 2.
Die für Prüfungen bei Beschleunigungs- und Bremsvorgängen festgelegten Verfahren sind Verfahren der Genauigkeitsklasse 3.
Applications ferroviaires - Acoustique - Mesurage du bruit à l'intérieur des véhicules circulant sur rails (ISO 3381:2021)
Le présent document spécifie la méthode de mesurage et les conditions nécessaires pour obtenir des niveaux de bruit reproductibles à bord de tous les types de véhicules circulant sur rails ou sur d'autres types de voies fixes, ci-après désignés «unité», à l'exception des véhicules de maintenance des voies fonctionnant en modes travail.
Le présent document s'applique aux essais de type. Il ne fournit pas toutes les instructions nécessaires pour effectuer les essais de surveillance ou l'évaluation de l'exposition des passagers ou des conducteurs au bruit pendant tout le trajet.
Le présent document ne s'applique pas aux autobus guidés.
Il fournit les procédures de mesurage permettant d'évaluer le bruit à l'intérieur du véhicule (en général, un essai de type du véhicule est réalisé à l'aide d'un sous-ensemble sélectionné de ces essais uniquement):
— lorsque le véhicule circule à vitesse constante;
— lorsque le véhicule est à l'arrêt;
— lorsque le véhicule est en phase d'accélération ou de décélération;
— dans la cabine de conduite lorsqu'un avertisseur sonore extérieur retentit (nécessaire en particulier pour l'application de la réglementation de l'Union européenne).
Le présent document ne fournit pas les procédures de mesurage pour évaluer:
— l'audibilité ou l'intelligibilité des signaux sonores;
— l'évaluation des dispositifs avertisseurs autres que les avertisseurs sonores.
L'évaluation de l'exposition du personnel de bord au bruit induit par les conditions d'exploitation ne relève pas du domaine d'application du présent document.
Les résultats peuvent être utilisés, par exemple, pour:
— caractériser le bruit émis à l'intérieur de ces unités;
— comparer les émissions de bruit intérieur de différentes unités sur une section de voie particulière;
— recueillir des données de base concernant les sources de bruit affectant les unités.
Les procédures d'essai spécifiées dans le présent document sont de la classe d'expertise (classe 2), qui est la classe préférentielle pour la déclaration du bruit, conformément à l'ISO 12001. Si les conditions d'essai sont assouplies (comme cela est le cas, par exemple, pour la surveillance des trains en service), alors les résultats ne relèvent plus de la classe d'expertise.
Les procédures spécifiées pour les essais d'accélération et de décélération font partie de la classe de contrôle (classe 3).
Železniške naprave - Akustika - Merjenje hrupa v tirnih vozilih (ISO 3381:2021)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2021
Nadomešča:
SIST EN 15892:2011
SIST EN ISO 3381:2011
Železniške naprave - Akustika - Merjenje hrupa v tirnih vozilih (ISO 3381:2021)
Railway applications - Acoustics - Noise measurement inside railbound vehicles (ISO
3381:2021)
Bahnanwendungen - Akustik - Geräuschmessungen in spurgebundenen Fahrzeugen
(ISO 3381:2021)
Applications ferroviaires - Acoustique - Mesurage du bruit à l'intérieur des véhicules
circulant sur rails (ISO 3381:2021)
Ta slovenski standard je istoveten z: EN ISO 3381:2021
ICS:
17.140.30 Emisija hrupa transportnih Noise emitted by means of
sredstev transport
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 3381
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2021
EUROPÄISCHE NORM
ICS 17.140.30; 45.020 Supersedes EN 15892:2011, EN ISO 3381:2011
English Version
Railway applications - Acoustics - Noise measurement
inside railbound vehicles (ISO 3381:2021)
Applications ferroviaires - Acoustique - Mesurage du Bahnanwendungen - Akustik - Geräuschmessungen in
bruit à l'intérieur des véhicules ferroviaires circulant spurgebundenen Fahrzeugen (ISO 3381:2021)
sur rails (ISO 3381:2021)
This European Standard was approved by CEN on 10 September 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 3381:2021 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 3381:2021) has been prepared by Technical Committee ISO/TC 43 "Acoustics"
in collaboration with Technical Committee CEN/TC 256 “Railway applications” the secretariat of which
is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2022, and conflicting national standards shall
be withdrawn at the latest by September 2024.
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.
This document supersedes EN 15892:2011 and EN ISO 3381:2011.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN websites.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: 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 3381:2021 has been approved by CEN as EN ISO 3381:2021 without any modification.
INTERNATIONAL ISO
STANDARD 3381
Third edition
2021-09
Railway applications — Acoustics —
Noise measurement inside railbound
vehicles
Applications ferroviaires — Acoustique — Mesurage du bruit à
l'intérieur des véhicules circulant sur rails
Reference number
ISO 3381:2021(E)
©
ISO 2021
ISO 3381:2021(E)
© 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
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
ISO 3381:2021(E)
Contents Page
Foreword .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Instrumentation and calibration . 3
4.1 Instrumentation . 3
4.2 Calibration . 3
5 Measurement positions . 4
5.1 Division of the unit into areas . 4
5.1.1 General. 4
5.1.2 Definition of area types . 4
5.1.3 Definition of area acoustics . 4
5.1.4 Selection of areas to be assessed . 4
5.2 Measurement positions . 6
5.3 Measurement height . 7
5.3.1 Seating position . 7
5.3.2 Standing position . . 7
5.3.3 Lying position . 7
5.3.4 Driving position . 8
6 Stationary test . 9
6.1 General . 9
6.2 Environmental conditions . 9
6.2.1 Acoustical environment . 9
6.2.2 Meteorological conditions . 9
6.2.3 Background sound pressure level .10
6.3 Track conditions .10
6.4 Vehicle conditions .10
6.4.1 General.10
6.4.2 Normal operating conditions .10
6.4.3 Additional operating conditions.11
6.5 Measured quantities .11
6.6 Test procedure .11
6.7 Data processing .11
6.7.1 Standard processing .11
6.7.2 Additional processing .12
7 Testing in cabs when sounding an external warning horn .12
7.1 Environmental conditions .12
7.1.1 Acoustical environment .12
7.1.2 Meteorological conditions .13
7.1.3 Background sound pressure level .13
7.2 Track conditions .13
7.3 Vehicle conditions .13
7.4 Measured quantities .13
7.5 Test procedure .13
7.6 Data processing .14
7.6.1 Standard processing .14
7.6.2 Additional processing .14
8 Constant speed test .14
8.1 General .14
8.2 Environmental conditions .14
8.2.1 Acoustical environment .14
8.2.2 Meteorological conditions .15
ISO 3381:2021(E)
8.2.3 Background sound pressure level .15
8.3 Track conditions .15
8.3.1 General.15
8.3.2 Track design .15
8.3.3 Track superstructure .16
8.3.4 Track quality .16
8.3.5 Rail roughness and track dynamic properties .16
8.3.6 Special conditions .16
8.4 Vehicle conditions .16
8.4.1 General.16
8.4.2 Normal operating conditions .17
8.4.3 Occupancy and load .17
8.4.4 Wheel tread conditioning .17
8.4.5 Additional conditions .18
8.5 Measured quantities .18
8.6 Test procedure .18
8.6.1 General.18
8.6.2 Test speeds .18
8.6.3 Measurement time intervals .18
8.7 Data processing .19
8.7.1 Standard processing .19
8.7.2 Additional processing .19
9 Acceleration from stand-still test and deceleration to stand-still test .20
9.1 General .20
9.2 Environmental conditions .20
9.2.1 Acoustical environment .20
9.2.2 Meteorological conditions .20
9.2.3 Background sound pressure level .21
9.3 Track conditions .21
9.4 Vehicle conditions .21
9.4.1 General.21
9.4.2 Normal operating conditions .22
9.4.3 Occupancy and load .22
9.4.4 Wheel tread conditions .22
9.5 Test procedure for the acceleration test .23
9.6 Test procedure for the deceleration test .23
9.7 Maximum level method .23
9.7.1 Measured quantities .23
9.7.2 Data processing .23
9.8 Averaged level method .24
9.8.1 Measured quantity .24
9.8.2 Data processing .24
10 Quality of the measurements .25
10.1 Deviations from the requirements .25
10.2 Positional tolerances .25
10.3 Measurement spread .25
10.4 Measurement uncertainties .25
11 Test report .25
Annex A (informative) Guidance on the definition and reporting of vehicle conditions .27
Annex B (informative) Method to characterize the impulsive character of the noise .28
Annex C (normative) Acoustic track characteristics .30
Annex D (informative) Specific environments .34
Annex E (informative) Quantification of measurement uncertainties according to
ISO/IEC Guide 98-3 .37
iv © ISO 2021 – All rights reserved
ISO 3381:2021(E)
Bibliography .41
ISO 3381:2021(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.
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 the European Committee for Standardization (CEN) Technical
Committee CEN/TC 256, Railway applications, in collaboration with ISO Technical Committee
ISO/TC 43, Acoustics, Subcommittee SC 1, Noise, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 3381:2005), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— new structure of the document to align it with the structure of ISO 3095;
— an improved selection process of the measurement positions – see Clause 5;
— new measurement procedures for noise in driver's cab – see Clause 7;
— improved specifications of the vehicle conditions for the different types of tests - see 6.4, 7.3, 8.4 and
9.4;
— an improved assessment of the tonality - see 6.7, 8.7 and 9.8.2.
— an improved indirect assessment of the track acoustic characteristics – see 8.3.4, 9.3 and Annex C;
— precisions for measurement in specific environments (tunnels, …) – see Annex D;
— an assessment of measurement uncertainties – see Annex E.
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.
vi © ISO 2021 – All rights reserved
INTERNATIONAL STANDARD ISO 3381:2021(E)
Railway applications — Acoustics — Noise measurement
inside railbound vehicles
1 Scope
This document specifies the measurement method and conditions to obtain reproducible noise levels
on-board all kinds of vehicles operating on rails or other types of fixed track, hereinafter conventionally
called “unit”, except for track maintenance vehicles in working modes.
This document is applicable to type testing. It does not include all the instructions to carry out
monitoring testing or evaluation of noise exposure of passengers or drivers over a whole journey.
This document is not applicable to guided buses.
It provides measurement procedures for vehicle interior noise (in general, a vehicle type test is carried
out using only a selected subset of these tests):
— when the vehicle is moving at constant speed;
— when the vehicle is stationary;
— when the vehicle is accelerating or decelerating;
— in the driver's cab when an external warning horn is sounding (specifically required for European
Union regulation application)
It does not provide measurement procedures for:
— audibility or intelligibility of any audible signals;
— assessment of warning devices other than warning horns.
The assessment of noise exposure of train crew due to operational conditions is not in the scope of this
document.
The results can be used, for example:
— to characterise the noise inside these units;
— to compare the internal noise of various units on a particular track section;
— to collect basic source data for units.
The test procedures specified in this document are of engineering grade (grade 2), the preferred grade
for noise declaration purposes as defined in ISO 12001. If test conditions are relaxed, for example as
they are for monitoring of in-service trains, then the results are no longer of engineering grade.
The procedures specified for accelerating and decelerating tests are of survey grade (grade 3).
2 Normative references
The following referenced documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For undated references the latest edition of the
referenced document (including any amendments) applies.
ISO 1996-1:2016, Acoustics — Description, measurement and assessment of environmental noise — Part 1:
Basic quantities and assessment procedures
ISO 3381:2021(E)
ISO 1996-2:2017, Acoustics — Description, measurement and assessment of environmental noise — Part 2:
Determination of sound pressure levels
IEC 60942, Electroacoustics — Sound calibrators
IEC 61260-1, Electroacoustics — Octave-band and fractional-octave-band filter — Part 1: Specifications
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
EN 15153-2:2020, Railway applications — external visible and audible warning devices — part 2: warning
horns for heavy rail
EN 15461:2008+A1: 2010, Railway applications — Noise emission — Characterization of the dynamic
properties of track sections for pass by noise measurements
EN 15610, Railway applications — Acoustics — Rail and wheel roughness measurement related to noise
generation
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 https:// www .electropedia .org/
3.1
unit
rolling stock which is subject to the application of this document
Note 1 to entry: A unit can be composed of several powered or unpowered vehicles, or cars.
3.2
type test
measurement performed to prove that, or to check if, a
unit delivered by the manufacturer complies with the noise specifications
3.3
acoustic roughness
r(x)
variation of the height of the rail running surface associated with rolling noise excitation, expressed as
a function of distance x along the rail
[SOURCE: EN 15610:2019]
3.4
track decay rate
rate of attenuation of vibration amplitude of either vertical or lateral bending wave motion in the rail as
a function of the distance along the rail
Note 1 to entry: The track decay rate is represented by a one-third octave spectrum of values expressed in
decibels per metre (dB/m) representing attenuation over distance.
[SOURCE: EN 15461:2008+A1: 2010]
3.5
acoustic track characteristics
ATC
characteristics of the track that are defined in terms of acoustic rail roughness and track decay rates
(3.4)
2 © ISO 2021 – All rights reserved
ISO 3381:2021(E)
3.6
test section
specific section of track that is associated with a particular set of measurements
3.7
impulsive sound
sound characterized by one or more brief bursts of sound pressure and that is such that the duration of
a single impulsive noise is usually less than 1 s
EXAMPLE Noise from blowoff valves, relay switches.
Note 1 to entry: The quantification of impulsiveness is set out in Annex B.
[SOURCE: ISO 1996-1:2016, 3.4.8, modified – "brief bursts of sound pressure" replaced with "one or
more brief bursts of sound pressure"; former Note 1 to entry is incorporated into the definition as "and
that is such that the duration of a single impulsive noise is usually less than 1 s"; Example and new Note
1 to entry added.]
3.8
intermittent source
source that operate at regular or irregular time intervals and is such that its duration is short
EXAMPLE Noise from compressors, exhaust fans, door operation, toilet.
3.9
tonal sound
sound characterized by a single frequency component or narrow band components that emerge audibly
from the total sound
[SOURCE: ISO 1996-1:2016, 3.4.9]
4 Instrumentation and calibration
4.1 Instrumentation
The microphones, signal acquisition units and processing algorithms used shall each comply with the
requirements of IEC 61672-1 specifications for class 1 measuring equipment.
NOTE Multichannel acquisition systems are generally used to record data.
In the case of measurements of survey grade, this requirement is relaxed to class 2 instruments.
The sound calibrator shall meet the requirements of class 1 according to IEC 60942.
Microphones with free-field or diffuse-field characteristics shall be used. A suitable microphone
windscreen should be used.
Where one-third octave frequency band analysis is required, the filters shall meet the requirements of
class 1, according to IEC 61260-1.
The conformity of the calibrator with the requirements of IEC 60942 shall have been verified within
one year of the test date. The conformity of the instrumentation system with the requirements of
IEC 61672 series shall have been within two years of the test date. The date of the last verification of the
conformity with the relevant standards shall be recorded.
4.2 Calibration
Before and after each series of measurements, a sound calibrator shall be applied to the microphone(s)
for verifying the calibration of the entire measuring system at one or more frequencies over the
ISO 3381:2021(E)
frequency range of interest. If the difference between the two calibrations is more than 0,5 dB, all the
measurement results in between shall be rejected.
The sensitivity of the measurement chain actually applied in the field shall be documented.
5 Measurement positions
5.1 Division of the unit into areas
5.1.1 General
The entire unit shall be divided into areas. Each area being defined by its type (see 5.1.2) and acoustic
characteristics (see 5.1.3).
5.1.2 Definition of area types
Area types are distinguished by their purpose, for example: passenger areas, seating (first class,
standard class), standing areas (including aisles), gangway, driver's cab, train manager compartment,
galley, lavatories, entrance, lobbies, restaurant, quiet, sleeping or resting areas.
The range of characteristics to be found within an area type depends upon the vehicle type and the
proposed operation schemes.
NOTE For example, for trams and metros, it can be appropriate to define a 'passenger area' that does not
distinguish between seating and standing areas.
5.1.3 Definition of area acoustics
The acoustics characteristics of areas are distinguished by their acoustic boundaries.
Examples for acoustic boundaries are:
— partition walls;
— draught screens;
— internal doors;
— decks of double deckers.
5.1.4 Selection of areas to be assessed
The number of discrete areas to be characterized by measurement may be reduced by identifying
discrete areas that are similar in terms of their type and acoustics characteristics. See Figures 1, 2 and
3.
No area shall cross the boundaries of an acoustic space (partition, wall, doors, …) and of a single vehicle.
For example, in double-deckers, decks shall be considered as separate areas.
Where there is no specification of the area types to be assessed, a minimum selection may be done
assuming that the noise criteria apply only to areas of the types with permanent passenger seats.
Areas to be assessed may be selected taking into account additional criteria (e.g. contractual
requirements in a project that can focus on seating area over a bogie, seating area close to a vestibule,
…). In dividing the unit into areas, bear in mind two objectives:
a) the efficiency of identifying similar areas to reduce the measurement effort, and
b) compatibility with the level of detail in the stated noise criteria.
4 © ISO 2021 – All rights reserved
ISO 3381:2021(E)
Key
a
Selection as a function of seating (areas A and D), multipurpose and vestibule (areas B and C).
b a
The same case as , but include differentiation between floor heights (subdivision of areas A and D).
Figure 1 — Example of a possible choice of areas to be assessed dividing 2 vehicles of a multiple
unit
Key
A first car
B second car
NOTE The gangway between the 2 cars is open and not considered as a specific area but included in area A.
Figure 2 — Example of definition of areas (A and B) in the case of a driverless metro
ISO 3381:2021(E)
Key
A, B and C areas
D passenger door
S passenger seats
NOTE Areas with seats (A and C); Vestibule areas (B). Areas A are C differentiated in terms of their acoustic
boundaries.
Figure 3 — Example of passenger coach divided into areas
5.2 Measurement positions
Measurements shall be carried out in at least one example of each similar area identified in 5.1 (e.g. one
example of each of the areas “A”, “B” and “C” in Figure 3).
If measurements are carried out for multiple examples of similar areas, results shall be averaged.
NOTE 1 In that case, the symmetry of the vehicle can be used as a justification to minimize the number of
similar areas to be measured (see Figure 4, in which the white character areas can be omitted based on symmetry
of the layout.)
Key
A, B and C areas
D passenger door
S passenger seats
Figure 4 — Example of selection of similar measurement areas
Each discrete area that is to be assessed shall be divided into equal segments of maximum length 5 m
along the unit, and each segment shall contain at least one measurement position (e.g. see Figure 5).
NOTE 2 This document leaves the freedom to choose measurement locations over a seat or between seats at
the same height in order to provide a representative sample of an area.
Some measurement positions can be omitted.
Measurement positions shall not be located closer than 0,3 m to a wall, screen or door.
NOTE 3 Microphone positions at this distance from boundary surfaces are representing the sound field heard
by passengers.
Additional measurement positions may be defined but shall be reported separately and not as part of
the characterization of an area.
6 © ISO 2021 – All rights reserved
ISO 3381:2021(E)
Key
S passenger seat (permanent longitudinal type) L length of a unit
D passenger door L length of a segment (<5 m)
s
M measurement position
Figure 5 — Example of definition of measurement positions for commuter units
(measurement height H = 1,2 m)
5.3 Measurement height
5.3.1 Seating position
In areas, other than the driver's cab, that contain permanent seats, the measurement height shall be set
to 1,2 m above the floor at the seat location. See Figure 6.
Dimensions in metres
Figure 6 — Examples of possible measurement positions for a seating area
5.3.2 Standing position
In standing areas, other than the driver's cab, measurements shall be located at a height of 1,6 m above
the floor.
5.3.3 Lying position
At locations where people are supposed to rest in horizontal position, the microphone positions shall be
0,2 m above the support.
ISO 3381:2021(E)
5.3.4 Driving position
When the cab contains more than one set of complete driving controls, the test shall be carried out at
each of these positions. This is not necessary at auxiliary driving positions where a full set of controls
is not present.
In a driver's cab area, the seated measurement position height shall be set at H=0,80 m ± 0,05 m
vertically above the centroid of the unloaded seat surface and offset 0,25 m ± 0,05 m laterally (see
Figure 7).
If the seat height is adjustable, this adjustment shall be set at midrange. For a suspended seat, the seated
measurement height shall be taken from a reference of mid-stroke position. The height of this nominal
position for the driver's seat above the floor shall be recorded.
In addition, a minimum distance of 0,3 m from the nearest wall shall be kept. The precise location of the
microphone shall be recorded.
For the warning horn test (see Figure 8 and Clause 7), the measurement shall be carried out at eight
evenly spaced microphone positions in a horizontal plane at the height of a seated measurement position
(H=0,80 m ± 0,05 m), at a radius of 0,25 m ± 0,05 m, while the external warning horn is sounding. Where
one or more of the required eight measurement positions is either not possible to realise because of
the presence of structural elements, or where it is within 0,2 m of an acoustically-reflective surface,
a measurement shall not be required at that position. The number of discrete measurement locations
shall then be reduced accordingly to N < 8. In case a headrest presents a hindrance to mounting the
microphones, it is permissible to remove the headrest or to use a measurement height as close as
possible to the specified
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