SIST EN ISO 11690-1:1997

SLOVENSKI STANDARD
SIST EN ISO 11690-1:1997
01-april-1997
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6WUDWHJLMDREYODGRYDQMDKUXSD,62
Acoustics - Recommended practice for the design of low-noise workplaces containing
machinery - Part 1: Noise control strategies (ISO 11690-1:1996)
Akustik - Richtlinien für die Gestaltung lärmarmer maschinenbestückter Arbeitsstätten -
Teil 1: Allgemeine Grundlagen (ISO 11690-1:1996)
Acoustique - Pratique recommandée pour la conception de lieux de travail a bruit réduit
contenant des machines - Partie 1: Stratégies de réduction du bruit (ISO 11690-1:1996)
Ta slovenski standard je istoveten z: EN ISO 11690-1:1996
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
SIST EN ISO 11690-1:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11690-1:1997

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SIST EN ISO 11690-1:1997

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SIST EN ISO 11690-1:1997

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SIST EN ISO 11690-1:1997

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SIST EN ISO 11690-1:1997

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SIST EN ISO 11690-1:1997
INTERNATIONAL IS0
STANDARD 11690-I
First edition
1996-l I-01
Acoustics - Recommended practice for
the design of low-noise workplaces
containing machinery -
Part 1:
Noise control strategies
Pratique recommandhe pour la conception de iieux de travail
Acoustique -
i bruit r6duit contenant des machines -
Partie 1: Strathgie de kduction du bruit
Reference number
IS0 11690-1:1996(E)

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SIST EN ISO 11690-1:1997
IS01 1690-l :1996(E)
Contents
Page
1
1 Scope .
2 Normative references . 1
3 Definitions . 2
4 . 7
Basic concepts in noise control
5 Assessment of the noise situation . 9
6 Parties involved . 10
7 How to tackle noise problems in workplaces . 10
a What to do before buying a new machine . 15
9 Noise prediction as a planning tool .
19
10 Long-term noise control programme . 20
Annex
A Bibliography
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 22
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii

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SIST EN ISO 11690-1:1997
@ IS0 ISO11690-1:1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide fed-
eration of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0 collabo-
rates closely with the International Electrotechnical Commission (IEC) on
all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are cir-
culated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 11690-I was prepared by Technical Committee
lSO/TC 43, Acoustics, Subcommittee SC 1, Noise.
IS0 11690 consists of the following parts, under the general title Acous-
tics - Recommended practice for the design of low-noise workplaces
containing machinery:
- Part I: Noise control strategies
- Par? 2: Noise control measures
Part 3: Sound propagation and noise prediction in workrooms
Part 1 is the central document in the series. Parts 2 and 3 give additional
technical and explanatory information. It is therefore recommended to start
with part I.
Annex A of this part of IS0 11690 is for information only.
. . .
III

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SIST EN ISO 11690-1:1997
IS0 11690-1:1996(E)
@ IS0
trod uction
Most of the existing International Standards prepared in ISO/TC 43/SC 1
specify methods for measurement and/or evaluation of noise. The final
objective of IS0 11690, however, is noise reduction.
A number of noise control measures are offered. However, in order to be
effective, the most appropriate noise control measure(s) should be chosen
for a given situation.
It is important when non-acoustic engineers are involved in noise control
practice for these engineers to have a basic knowledge of noise emission
and propagation characteristics and to understand the basic principles of
noise control.
To assist in the development of noise control in the workplace, it is essen-
tial that the information contained in these recommended practices is dis-
seminated through International Standards.
In order to reduce noise as a hazard in the workplace, individual countries
have produced national legislation. Generally, such national legislation
requires noise control measures to be carried out in order to achieve the
lowest reasonable levels of noise emission, noise immission and noise ex-
posure, taking into account:
- known available measures;
- the state of the art regarding technical progress;
the treatment of noise at source;
-
- appropriate planning, procurement and installation of machines and
equipment.
This part of IS0 11690, together with the two other parts in the series, out-
lines procedures to be considered when dealing with noise control at
workplaces, within workrooms and in the open. These recommended prac-
tices give in relatively simple terms the basic information necessary for all
parties involved in noise control in workplaces and in the design of low-
noise workplaces to promote the understanding of the desired noise control
requirements.
The purpose of the IS0 11690 series is to bridge the gap between existing
literature on noise control and the practical implementation of noise control
measures. In principle, the series applies to all workplaces and its main
function is:
- to provide simple, brief information on some aspects of noise control
in workplaces;
- to act as a guide to help in the understanding of requirements in stan-
dards, directives, text books, manuals, reports and other specialized
technical documents;

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SIST EN ISO 11690-1:1997
@ IS0 IS0116904:1996(E)
- to provide assistance in decision making when assessing the various
measures available.
The IS0 11690 series should be useful to persons such as plant person-
nel, health and safety officers, engineers, managers, staff in planning and
purchasing departments, architects and suppliers of plants, machines and
equipment. However, the above-mentioned parties should keep in mind
that adherence to the recommendations of the IS0 11690 series is not all
that is necessary to create a safe workplace.
The effects of noise on health, well-being and human activity are many. By
giving guidelines for noise control strategies and measures, the IS0 11690
series aims at a reduction of the impact of noise on human beings at
workplaces. Assessment of the impact of noise on human beings is dealt
with in other documents.

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SIST EN ISO 11690-1:1997
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SIST EN ISO 11690-1:1997
IS0 116904 : 1996(E)
INTERNATIONAL STANDARD @ IS0
- Recommended practice for the design of low-noise
Acoustics
workplaces containing machinery -
Part 1:
Noise control strategies
IS0 3740:1980, Acoustics - Determination of sound
1 Scope
power levels of noise sources - Guidelines for the
use of basic standards and for the preparation of noise
This part of IS0 11690 outlines strategies to be used
test codes.
in dealing with noise problems in existing and planned
workplaces by describing basic concepts in noise
control (noise reduction, noise emission, noise immis- IS0 3741 :I 988, Acoustics - Determination of sound
sion and noise exposure). It is applicable to all types of power levels of noise sources - Precision methods
workplaces and all types of sources of sound which for broad-band sources in reverberation rooms.
are met in workplaces, including human activities.
IS0 374211988, Acoustics - Determination of sound
It includes those important strategies to adopt when
power levels of noise sources - Precision methods
buying a new machine or equipment.
for discrete-frequency and narrow-band sources in re-
verbera tion rooms.
This part of IS0 11690 deals only with audible sound.
IS0 3743-l :I 994, Acoustics - Determination of
sound power levels of noise sources - Engineering
2 Normative references methods for small, movable sources in reverberant
fields - Part 1: Comparison method for hard-walled
The following standards contain provisions which,
test rooms.
through reference in this text, constitute provisions of
this part of IS0 11690. At the time of publication, the
IS0 3743-211994, Acoustics - Determination of
editions indicated were valid. All standards are subject
sound power levels of noise sources using sound
to revision, and parties to agreements based on this
pressure - Engineering methods for small, movable
part of IS0 11690 are encouraged to investigate the
sources in reverberant fields - Part 2: Methods for
possibility of applying the most recent editions of the
special reverberation test rooms.
standards indicated below. Members of IEC and IS0
maintain registers of currently valid International Stan-
IS0 374411994, Acoustics - Determination of sound
dards.
power levels of noise sources using sound pressure
- Engineering method in an essentially free field over
IS0 1996-1:1982, Acoustics - Description and
a reflecting plane.
measurement of environmental noise - Part 1: Basic
quantities and procedures.
IS0 37451977, Acoustics
- Determination of sound
power levels of noise sources - Precision methods
IS0 1996-2:1987, Acoustics - Description and
for anechoic and semi-anechoic rooms.
measurement of environmental noise - Part 2:
Acquisition of data pertinent to land use.
IS0 3746: 1995, Acoustics - Determination of sound
IS0 1999:1990, Acoustics - Determination of occu- power levels of noise sources using sound pressure
pational noise exposure and estimation of noise- - Survey method using an enveloping measurement
surface over a reflecting plane.
induced hearing impairment.

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SIST EN ISO 11690-1:1997
0 IS0
IS0 11690-l : 1996(E)
IEC 651 :I 979, Sound level meters.
IS0 374711987, Acoustics - Determination of sound
power levels of noise sources - Survey method using
a reference sound source.
IEC 804: 1985, Integrating-averaging sound level me-
ters.
IS0 4871 :I 996, Acoustics - Declaration and verifi-
cation of noise emission values of machinery and
equipment.
3 Definitions
IS0 9614-I :I 993, Acoustics - Determination of
sound power levels of noise sources using sound
For the purposes of this part of IS0 11690, the follow-
intensity - Part I: Measurement at discrete points.
ing definitions apply.
9614-2:1996, Acoustics - Determination of
IS0
sound power levels of noise sources using sound in-
tensity - Part 2: Measurement by scanning.
3.1 Genera I noise descriptors
IS0 11200:1995, Acoustics - Noise emitted by ma-
3.1 .l sound pressure level, Lp: Ten times the
chinery and equipment - Guidelines for the use of
logarithm to t he base IO of the ratio of the mean-
basic standards for the determination of emission
square sound pressure (p, in pascals) to the square of
sound pressure levels at a work station and at other
the reference sound pressure (pO = 20 PPa).
specified positions.
IS0 11201 :I 995, Acoustics - Noise emitted by ma-
chinery and equipment - Measurement of emission
sound pressure levels at a work station and at other
Engineering method in an es-
specified positions -
The sound pressure level is the main quantity to de-
sentially free field plane.
scribe the noise at a given point. It is expressed in
decibels and shall be measured with a standardized
IS0 11202:1995, Acoustics - Noise emitted by ma-
sound level meter (see IEC 651).
chinery and equipment - Measurement of emission
sound pressure levels at a work station and at other
The frequency weighting (A or C) or the width of the
specified positions - Survey method in situ.
frequency band and the time weighting (S, F, I or peak)
used shall be indicated.
IS0 11203:1995, Acoustics - Noise emitted by ma-
chinery and equipment - Determination of emission
NOTES
sound pressure levels at a work station and at other
specified positions from the sound power level.
1 For example, the C-weighted sound pressure level with
time weighting peak is Lpc peak.
,
IS0 11204:1995, Acoustics - Noise emitted by ma-
chinery and equipment - Measurement of emission 2 The notation Lp is used whether the sound pressure
level refers to emission (see 3.2), immission or exposure
sound pressure levels at a work station and at other
(see 3.3).
specified positions - Method requiring environmental
corrections.
3.1.2 time-averaged sound pressure level, Lpes T:
ISOKR 11688-l :I 995, Acoustics - Recommended
Sound pressure level of a continuous steady sound
practice for the design of low-noise machinery and
that within a measurement time interval, T, has the
equipment - Part I: Planning.
same mean square sound pressure as a sound under
consideration which varies with time; it is the level of
IS0 11689:1996, Acoustics - Procedure for the com-
the mean square sound pressure over a time interval.
parison of noise-emission data for machinery and
It is expressed in decibels.
equipment.
IS0 11690-2:1996, Acoustics - Recommended prac-
L IOlg
peq,T =
tice for the design of low-noise workplaces containing
machinery - Part 2: Noise control measures.

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SIST EN ISO 11690-1:1997
IS0 11690-l : 1996(E)
@ IS0
3.2.4 surface sound pressure level, Lp~d: The
The time-averaged sound pressure level is the main
A-weighted sound pressure level averaged on an en-
quantity to assess the immission at work stations and
ergy basis over a measurement surface at a distance
the exposure of persons. It is then called the equiva-
lent continuous sound pressure level. d from the sound source (see IS0 3744). When
d = 1 m, it is usually noted Lp~ 1 m.
B
NOTES
3 When immission or exposure is considered, impulse and
3.2.5 measured noise emission value, L: Any of
tone adjustments, DLr and DLT, in decibels, may be used to
the A-weighted sound power level, the A-weighted
take into account the influence of impulsive and tonal com-
time-averaged emission sound pressure level, or the
ponents (LpAeq T + DLr + DLT) (see IS0 1996-1, IS0 1996-2
C-weighted peak emission sound pressure level, de-
and IS0 1999):
termined from measurements. Measured values may
4 Subscript “eq,T” is often omitted because in all cases be determined either for a single machine or from the
considered in this part of IS0 11690 the sound pressure is
average of a number of machines. They are ex-
averaged over a certain measurement time interval (see
pressed in decibels and are not rounded.
IEC 804).
3.2.6 noise emission declaration: The information
3.1.3 work station: A position, in the vicinity of a
on the noise emitted by the machine, given by the
machine, which can be occupied by the operator or
manufacturer or the supplier in technical documents or
a position where a task is carried out.
other literature, concerning noise emission values.
The noise emission declaration may take the form of
either the declared single-number noise emission
3.2 Noise emission descriptors
value or the declared dual-number noise emission
value.
3.2.1 noise emission: Airborne sound radiated into
the environment from a defined source (machine or
equipment). [See figure 1 a).]
3.2.7 uncertainty, K: The numerical value of the
measurement uncertainty associated with a measured
noise emission value.
3.2.2 sound power level, Lw: Ten times the loga-
rithm to the base IO of the ratio of the sound power (P,
in watts) radiated by the sound source under test to
3.2.8 declared single-number noise emission
the reference sound power (PO = 1 pW).
value, Ld: The sum of a measured noise emission
value and the associated uncertainty, rounded to the
It is expressed in decibels and is a descriptor of the
nearest decibel:
emission of a sound source (see the IS0 3740 and
IS0 9614 series). The frequency weighting or the
&-j=L+K
width of the frequency band used shall be indicated.
NOTE 5 For example, the A-weighted sound power level is
3.2.9 declared dual-number noise emission value,
LWA-
L and K: A measured noise emission value and its
associated uncertainty, K, both rounded to the nearest
3.2.3 emission sound pressure level, Lp: The
decibel.
sound pressure level caused by a sound source under
test at its work station or at any other specified posi-
tion. It is expressed in decibels and is an additional
descriptor of the emission of a sound source (see
3.3 Noise immission and noise exposure
IS0 11200 to IS0 11204).
3.3.1 noise immission at a work station: All noises
The frequency weighting and/or the time weighting or
that arrive, whether or not a worker is present, over a
the width of the frequency band used shall be indi-
specific time period T, at a measuring point (work sta-
cated.
tion) in the actual situation; i.e. noise coming from the
machine, noise coming from the other sound sources
NOTES
and noise reflected by the ceiling, the walls and any
fittings. [See figure 1 b).]
6 For example, the C-weighted peak emission sound
pressure level is f& peak.
,
NOTE 8 T can be the duration of a measurement, an op-
erating cycle of a machine, a process, the duration a worker
7 The A-weighted emission sound pressure level is often
averaged over an operational period of a sound source; it is is usually present at or near the measurement point, or the
duration of the workshift.
denoted Lp~.
3

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SIST EN ISO 11690-1:1997
ISO11690-1:1996(E)
a) Noise emission; sound radiation of a machine:
- machine related
- specified operating conditions
- independent of environment
b) Noise immission: sound impact at the work station:
‘-
- work station related
\
- real operation
- dependendent on imm ssion time
-.
- contribution from all
sound sources
cl Noise exposure; sound impact on human beings:
- person related Cat one or several work stations or for a person moving around
(see figure 211
- real operation
-dependentonexposuretime
- contribution from all sound sources
Figure 1 - Illustration of the difference between noise emission, noise immission and noise exposure
(see also figure 2)
4

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SIST EN ISO 11690-1:1997
IS0 11690-l : 1996(E)
@ IS0
Figure 2 - Illustration of noise exposure for a person moving around
3.4.2 sound absorption coefficient, a: The fraction
3.3.2 noise exposure of a person: All noises that
of the acoustic energy absorbed when sound waves
arrive, over a specific time period T, at a person’s ear
strike a surface. It is frequency dependent.
in the actual situation. [See figure lc) and figure 2.1
NOTE 10 A single number rating is given in IS0 11654.
3.3.3 noise immission and noise exposure de-
scriptors: The equivalent continuous A-weighted
sound pressure level normalized to a nominal working
tion area, A: The area ., in
3.4.3 equivalent absorp
day, $&q,&, in decibels:
.S.’
square meters, obtained by summing the p roducts a
1 I’
= LpAeq,T, + 10 b&/TO) dB
LpAwTo
A = a$, + cc2S2 + . . . =as
where TO is the reference duration (e.g. 8 h) and T, is
where
the duration of the workshift. lmmission is measured at
the work station. Exposure is measured at the ear of is the absorption coefficient of a partial area,
&
the person.
Sj, of a room surface;
S is the total room area (= XSj);
LpAeq,To can result from the energetic summation of
immission or exposure values, LpAeq,T;, measured
a is the mean absorption coefficient of the room.
over individual time periods Ti, with ETj = Te.
In some countries, a rating level Lp~r is used:
3.4.4 insertion loss, Di: The difference in sound
power level or emission sound pressure level with and
+ DLI + DLT dB
LpAr
= LpAeq,To
without a noise control device applied to a sound
source. Q is frequency dependent and is expressed in
where DLr and DLT describe impulsive and tonal com-
decibels. The A-weighted insertion loss is always re-
ponents.
lated to a given source.
NOTE 11 The insertion loss is used to assess the acousti-
3.4 Noise reduction
cal performance of enclosures (see IS0 11546-1 and
IS0 11546-2), screens (see IS0 10053 and IS0 11821) and
3.4.1 sound reduction index, R; A descriptor of silencers (see IS0 7235, IS0 11691 and IS0 11820).
transmission loss defined as ten times the logarithm to
the base 10 of the ratio of the sound power incident on
3.4.5 reduction of sound pressure level at a work
a test specimen to the sound transmitted through the
station: The result of a set of noise reduction meas-
test specimen. (See figure 3.) It is expressed in deci-
ures described by the difference in noise immission
bels and is frequency dependent.
levels.
NOTE 9 Methods for determining the insulation of walls,
doors, ceilings and windows are described in parts 1 to 10 NOTE 12 For example, $Aeq,8h,j - $&q,Jh,2, where nU-
of IS0 140 (frequency band values) and in parts 1 and 3 of meral 1 means before and numeral 2 means after technical
IS0 717 (single number ratings). measures for reduction have been taken.
5

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SIST EN ISO 11690-1:1997
@ IS0
ISO11690-1:1996(E)
Reflection Absorption Transmission
NOTE - A proportion of the sound which is incident on a partition or wall is reflected, a proportion is transformed into heat
(i.e. is absorbed) and a proportion goes through the wall to the other side (i.e. is transmitted). The sound insulation of the wall
determines what proportion of the incident sound is transmitted.
Figure 3 - Illustration of reflection, absorption and transmission at a boundary
3.4.10 reverberation time, T: The time, in seconds,
3.4.6 direct sound: The sound which propagates
directly from the source to the point of observation. No it takes for the sound pressure level in a room
(originally in a steady state) to decrease 60 dB after
reflection of sound is involved so it is not affected by
the characteristics of the room in which the source is the source is turned off. (See figure 4.) The rever-
beration time is frequency dependent. It is useful for
located.
describing the acoustic properties of rooms with a
diffuse sound field; room volume must be taken into
3.4.7 reflected sound: The sound at any point in a
account.
room, resulting from reflections from room surfaces
and fittings. It does not include the direct sound.
3.4.11 spatial sound distribution curve: The curve
which shows how the sound pressure level from a ref-
3.4.8 diffuse-field conditions: Sound propagation in
erence sound source decreases when the distance to
rooms or regions of rooms where the sound is re-
the source increases. Such curves are frequency de-
flected so often and uniformly from all surfaces of the
pendent and characterize the acoustic properties of
room and the fittings that the sound pressure level of
rooms. In some cases, several spatial sound distribu-
the reflected sound is the same at any point inside the
tion curves are necessary to characterize a room.
region.
From this curve and for a given range of distances
3.4.9 non-diffuse-field conditions: Sound propaga-
from the source, two main quantities are determined
tion in rooms or regions of rooms where sound does
(see figure 5):
not propagate uniformly in all directions. This is the
case if
- the rate of spatial decay per distance doubling
p-2), and
- the ratio of any two dimensions out of the three is
- the excess of sound pressure level (DLf).
more than three, or
- the absorption of the surfaces of the room is no-
Three distance ranges are normally of interest: near,
tably non-uniformly distributed (e.g. a room with
middle and far regions. These two quantities (DL2,
hard walls and absorbent ceiling), or
DLf) are useful for assessing the acoustic quality of a
room.
- the absorption is high.
6

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SIST EN ISO 11690-1:1997
IS0 11690-l : 1996(E)
Time, s
NOTE - T is the reverberation time.
Idealized time history of sound pressure level after the sound source is turned off
Figure 4 -
3.4.12 rate of spatial decay of sound pressure when formulating a noise control strategy and imple-
menting noise control measures for new and existing
levels per distance doubling, DL2: The amount, in
workplaces.
decibels, by which the sound pressure level decreases
over a given range of distances, when the distance
from the source is doubled. (See figure 5.)
a) Determine objectives and establish criteria.
b) Carry out noise assessment by identifying:
3.4.13 excess of sound pressure level, DLf: The
average difference, in decibels, over a given distance
- the areas concerned,
range, between the spatial sound distribution curve of
the room and the spatial sound distribution curve for a
- the immission at work stations,
free field (6 dB per distance doubling). (See figure 5.)
- the contributions of different noise sources to
the immission at work stations,
- the exposure of persons,
4 Basic concepts in noise control
- the emission of sources in order to rank
4.1 Basic noise control strategy them.
Effective noise reduction will only be achieved by deal- c) Consider noise control measures such as:
ing with the problem in a systematic manner. Listed
- noise control at source,
below is a series of steps that should be considered
7

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SIST EN ISO 11690-1:1997
IS0 11690-l : 1996(E)
m
D
xi
>
aJ
-
aJ
5
E
(11
k
-cl
5
tz
I
2d ; 4d
d/2 i d
I
I
Distance from source - i
I
I
I I
I
Far region
Near region Middle region I
_)
I
I
Key
w Spatial sound distribution curve
----- Without reflections (free field)
- Example of:
Figure 5
(i) a spatial sound distribution curve for a room and for the free field;
(ii) the three ranges of distances;
(iii) the determination of the spatial decay (DL*);
and (iv) the excess (DLf) of sound pressure level
- noise control on the transmission path in the 4.2 Concept of noise reduction
workplace,
Noise control can be implemented using various tech-
- noise control at work stations.
nical measures (see IS0 11690-2) and there may be
several ways to solve a noise problem. These meas-
d) Formulate a noise control programme.
ures are noise reduction at source (e.g. machines,
working processes), noise reduction by increasing the
attenuation of sound during its propagation (e.g. using
e) Implement the appropriate measures.
enclosures, screens, absorbing linings), noise reduc-
tion at specific positions (e.g. using cabins).
f) Verify the noise reduction attained.
8

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SIST EN ISO 11690-1:1997
IS0 11690-l : 1996(E)
Regulations
Standards
User of technical equipment
Additional noise
reduction measures
Figure 6 - Factors affecting noise control
specified position for defined mounting and operating
Technical measures for noise control should be
conditions and due to the machine only.
applied in order to implement the state of the art with
regard to noise control. For this purpose, it is neces-
There are further noise emission quantities such as
sary to compare and determine the effectiveness of
frequency band levels, the C-weighted peak emission
these measures. Acoustical quantities are used for
sound pressure level at the work station and the time
this purpose. They describe the acoustical features of
history.
the sound sources, the noise reduction attained in
workplaces, and especially at work stations, when
Basic methods for measuring and declaring noise
sound sources are operating and some noise control
measures have been implemented. emission values are given in the IS0 3740 series, the
IS0 9614
...