ISO 9703-2:1994

INTERNATIONAL
IS0
STANDARD
9703-2
First edition
1994-l l-1 5
Anaesthesia and respiratory care alarm
signals -
Part 2:
Auditory alarm signals
Signaux d’alarme pour I’anesth&ie et /es soins respiratoires -
Partie 2: Signaux d’alarme auditifs
Reference number
IS0 97032: 1994(E)
IS0 9703-2: 1994(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation 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
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 9703-2 was prepared by Technical Committee
ISO/TC 121, Anaesthetic and respiratory equipment, Subcommittee
SC 3, Lung ventilators and related equipment.
IS0 9703 consists of the following parts, under the general title
Anaesthesia and respiratory care alarm signals:
- Part 1: Visual alarm signals
- Part 2: Auditory alarm signals
- Part 3: General requirements
- Part 4: Guidance on application
Annexes A and B of this part of IS0 9703 are for information only.
0 IS0 1994
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 photocopyrng and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-121 1 Geneve 20 l Switzerland
Printed in Switzerland
ii
0 IS0
IS0 9703-2: 1994(E)
Introduction
Medical practice in hospitals is increasingly dependent on medical devices
for observation and treatment of patients. Sounds and lights are frequently
used to indicate the patient’s physiological status and the functional state
of the medical device. The sounds used are frequently too loud and not
distinctive, and it is often difficult to identify which medical device is
signalling. The purpose of this part of IS0 9703 is to specify the auditory
component of alarm signals to be used to draw attention to the fact that
the medical device has detected a disturbance and to indicate the degree
of urgency.
This part of IS0 9703 was developed from contributions from clinicians,
engineers and applied psychologists. The approach taken is intended to
rationalize the current situation and to limit the proliferation of different
sounds, in order to avoid confusion.
Some of the criteria considered during development of the sounds in-
cluded optimal signal recognition in a relatively noisy environment, maxi-
mum transmission of information at the lowest practicable sound pressure
level, ease of learning and retention by operators who have to respond to
the various signals, and perceived urgency of the sounds.
Two important alarm signals are specified, i.e. high and medium priority
signals. The auditory signals are acoustically related, but are differentiated
by their perceived urgency. Guidelines are given for the design of a signal
of lower priority than that of medium priority, and also for an information
signal. Visual components are specified in IS0 9703-I.
NOTE 1 This International Standard is based on discussions held in lSO/TC 121
over a number of years, and on prEN 475, prepared by CEN/TC 259.
. . .
III
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INTERNATIONAL STANDARD 0 Iso IS0 9703=2:1994(E)
Anaesthesia and respiratory care alarm signals -
Part 2:
Auditory alarm signals
to revision, and parties to agreements based on this
1 Scope
part of IS0 9703 are encouraged to investigate the
possibility of applying the most recent editions of the
This part of IS0 9703 specifies the characteristics of
standards indicated below. Members of IEC and IS0
the auditory component of electrically generated pri-
maintain registers of currently valid International
mary alarm systems in anaesthesia and respiratory
Standards.
care, either individually or as part of a centralized
system. It applies only if a particular International
IS0 3744:1994, Acoustics - Determination of sound
Standard for a medical device makes reference to it.
power levels of noise sources using sound pressure
- Engineering method in an essentially free field over
This part of IS0 9703 does not specify
a reflecting plane.
a) the medical devices on which these alarms are to
IS0 9703-I :I 992, Anaesthesia and respiratory care
be provided;
alarm signals -
Part I: Visual alarm signals.
b) the conditions that actuate the alarms;
IS0 11201: --J), Acoustics - Noise emitted by ma-
c) the means of generating the alarm signals; chinery and equipment - Measurement of emission
sound pressure leveis at the work station and at other
d) secondary alarm system characteristics, i.e. alarm
specified positions - Engineering method in an es-
systems which are activated in case of a failure in
sentially free field over a reflecting plane.
the primary alarm system;
e) the allocation of priorities to alarms.
3 Definitions
NOTE 2 It is expected that requirements for the appli-
cation of the auditory alarm signals specified in this part of
For the purposes of this part of IS0 9703, the follow-
IS0 9703 will be included in “Particular Standards” (as for-
ing definitions apply.
mulated in IEC) for the particular medical devices.
3.1 alarm signal: Signal, the purpose of which is to
alert the operator to an abnormal condition which, if
not immediately or promptly attended to, may de-
2 Normative references
velop into a safety hazard.
The following standards contain provisions which,
through reference in this text, constitute provisions 3.2 information signal: Signal, the purpose of
of this part of IS0 9703. At the time of publication, the which is to convey physiological or technical infor-
mation.
editions indicated were valid. All standards are subject
1) To be published.
0 IS0
IS0 9703=2:1994(E)
3.3 high priority (warning) alarm: Signal indicating 3.17 repeat time: Period of time between the start
that immediate operator response is required. of the first pulse of a burst or the first pulse of a
double burst and the start of the first pulse of the next
(IS0 9703-I :I 992, definition 2.3)
burst or the first burst of the next double burst.
3.4 medium priority (cautionary) alarm: Signal in-
dicating that prompt operator response is required.
(IS0 9703-l :I 992, definition 2.4)
4 Requirements for signals
3.5 low priority (advisory) alarm: Signal indicating
that operator awareness is required. (IS0 9703-I:
4.1 Auditory alarm signals
1992, definition 2.5)
Auditory alarm signals shall meet the requirements
3.6 pulse: Brief sound having a specific frequency of tables 1 and 2, unless they are generated by means
of different technology, for example voice synthesiz-
spectrum.
ing. If a different technology is employed, it shall pre-
clude the possibility of confusion with the auditory
3.7 overall pulse duration (t,): Time over which the
signals specified in tables 1 and 2.
pulse amplitude exceeds 10 % of the maximum am-
plitude. (See figure 1.)
4.2 Composition of high priority alarm
3.8 rise time (t,): Time over which the pulse in-
signal
creases from 10 % to 90 % of maximum amplitude.
(See figure 1.)
A high priority alarm signal shall comprise a high pri-
ority auditory signal complying with tables 1 and 2,
3.9 start of pulse: Point at which the amplitude first
and a simultaneous high priority visual indication
exceeds 90 % of the maximum amplitude. (See
complying with IS0 9703-I.
figure 1.)
4.3 Composition of medium priority alarm
3.10 end of pulse: Point at which the amplitude first
signal
falls below 90 % of the maximum amplitude. (See
figure 1.)
A medium priority alarm signal shall comprise a me-
dium priority auditory signal complying with tables 1
3.11 effective pulse duration (td): Period of time
and 2, and a simultaneous medium priority visual in-
between start of pulse and end of the same pulse.
dication complying with IS0 9703-I.
(See figure 1.)
NOTE 3 Although to = tr + td + tP this part of IS0 9703 is
4.4 Composition of low priority alarm signal
written in terms of td because it is easier to measure.
If one or more levels of low priority alarm signals are
3.12 fall time (@: Time over which a pulse de-
employed, their auditory characteristics shall be dif-
creases from 90 % to IO % of maximum amplitude.
ferent from those of high and medium priorities. The
(See figure 1.)
sound shall be nonintrusive and nonstartling. Under
no circumstances shall the sound pressure level ex-
3.13 pulse frequency (fp): Fundamental frequency
ceed that of a medium priority signal. Both rise time
of a pulse.
and fall time shall not be less that 40 ms.
3.14 burst: Group of pulses with a distinctive
4.5 Composition of information signals
rhythm.
If information signals are employed, their auditory
3.15 pulse spacing (t,>: Period of time between the
characteristics shall be different from that of high and
start of one pulse and the start of the next pulse. (See
medium priority. The sound shall be nonintrusive and
figure 1.)
nonstartling. Under no circumstances shall the sound
pressure level exceed that of a medium priority signal.
3.16 burst spacing (lr.J: Period of time between the
Both rise time and fall time shall not be less than
start of the first pulse in one burst and the start of the
40 ms.
first pulse in the next burst. (See figure I.)

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IS0 9703-2: 1994(E)
ii ii
A
2. a
4- +
0 0
t
t
2 2
;fi; t;
tb (high priority aLarm ofdy)
Time, ms -
- This figure is intended to show the designation of temporal characteristics, and does not illustrate any individual
NOTE
auditory signal.
Figure 1 - Illustration of temporal characteristics of auditory signals
Table 2 - Characteristics of pulses
Table 1 - Characteristics of bursts
High Medium Characteristic Value
Characteristic
priority priority
150 Hz to 1000 Hz
Pulse frequency (Q 1)
5 3
Number of pulses in burst’)
Number of harmonic components
4 min.
in the range 300 Hz to 4000 Hz
Pulse spacing (Q 2)
x 3)
between 1 stand 2nd pulses
Y 4’
Effective pulse duration (QJ 150
...