Subclause 6.3.3.1 –
Characteristics of auditory ALARM SIGNALS
ü
A different
technology implies something other than electronically generated tones.
ü
There are a
variety of means for generating auditory ALARM SIGNALS, including buzzers, electronic sound generators
and speech synthesizers.
? At least
some of the methods described above can be used to indicate priority regardless
of the means of generating the signal.
Table 3 – Characteristics of the BURST
of auditory ALARM SIGNALS
Table
4 – Characteristics of the PULSE of auditory ALARM
SIGNALS
ü
Table 3 and Table 4 are based on the requirements for
auditory ALARM SIGNALS that were found in ISO 9703-2 [26]. These distinctive
patterns or rhythms have been used for more than a decade and have been well
accepted clinically. Table 3 and Table 4 are slightly different from the
equivalent tables in ISO 9703-2.
? The modifications were
intended to simplify interpretation and increase flexibility rather than
introduce significant change.
כיצד?
? Auditory ALARM SIGNALS that complied with ISO 9703-2 should also
comply with this collateral standard.
מדוע?
ü
Spatial localization of an auditory ALARM SIGNAL is useful
because it helps the OPERATOR to identify the source of the ALARM CONDITION promptly.
ü
Ensuring that four or more audible higher-frequency
harmonics are present in an auditory ALARM SIGNAL enhances spatial localization.
? Spatial localization is
poor at low frequencies, so the lower acceptable limit for fundamental
frequency is set at 150 Hz.
מסקנה
שגויה, לדעתי,
מכיוון
שההרמונית
הגבוהות מספקות
את הכיווניות.
מצד שני,
כנראה שמגבלה
זו אינה יוצרת
בעיה
ü
Hearing impairment from noise exposure or age usually
impairs perception of higher frequencies, so that to ensure that all harmonics
are audible, the upper limit for fundamental frequency is set at 1 000 Hz.
ü
Selection of the INTERBURST INTERVAL requires RISK ANALYSIS and careful consideration.
ü
Shorter INTERBURST INTERVALS can result in noise pollution and impair
communication among OPERATORS or other personnel who are trying to address the problem,
and are inappropriate for equipment that is intended to be continuously
attended by the OPERATOR in NORMAL USE. On the other hand, longer INTERBURST INTERVALS can negatively affect the ability of the OPERATOR to identify, in a timely manner, the
source of the ALARM CONDITION. This is particularly true for equipment intended to be
unattended by the OPERATOR in NORMAL USE.
נראה
לי שבמצב
שהמשתמש נמצא
ליד החולה
ומטפל בו, צריך
לאפשר לו או
לכבות את
ההתרעה זמנית (עם
תזכורת) או
לשלוט
במרווחי הזמן
בין מקבצי
התרעות.
? MANUFACTURERS are
encouraged to use the longest INTERBURST INTERVAL consistent with the RISK
ANALYSIS.
זוהי
מסקנה חלקית.
בסעיף הקודם
הוצגו שני
סיכונים. סעיף
זה מתייחס
לסיכון השני (למרות
שזה לא צוין
בפירוש).
ü
Writers of particular standards are encouraged to consider
the longest appropriate INTERBURST INTERVAL of the auditory ALARM SIGNAL for the particular ALARM SYSTEM application.
גם כאן,
ההתייחסות
היא לסכון
השני בלבד.
The main differences between ISO 9703-2
and this collateral standard and the reasons for the current requirements, are
described below:
כל הסעיף
הזה היה צריך
להופיע בדיון של
List element b) ולא
כאן
ü
The new PULSE spacing intervals are defined differently from ISO 9703-2
and provide greater design flexibility. PULSE spacing is now defined as the time from
the end of one PULSE to the start of the next. As a result there is no
possibility of overlap, which could occur in ISO 9703-2. The actual values
permit all auditory ALARM SIGNALS complying with ISO 9703-2 except for HIGH PRIORITY
ALARM SIGNALS in
which the PULSES almost
overlap. For obvious reasons, very few MANUFACTURERS actually did this. The committee
considered that PULSES should have reasonable gaps between them, and that near overlapping of PULSES should not be permitted.
M b) In ISO 9703-2, the
intended rhythm could not be achieved if each
PULSE spacing
was the same. The redrafted Table 3 addresses this problem. To ensure that the
distinctive pattern is achieved, yet provide some flexibility in overall
timing, this standard requires all INTERBURST INTERVALS within a BURST to have the same duration. A tolerance of
±5 % seemed appropriate.
לדעתי,
המרווחים
הקבועים
תורמים
לתחושת
החירום. המעבר
למרווחים
משתנים יוצר
אוירה של
חגיגה.
ü
c) The time between the two five-PULSE groups that comprise a HIGH PRIORITY
ALARM SIGNAL (time
between 5th and 6th PULSES) is now defined as the time from the end of the last PULSE in the first group to the start of the
first PULSE in
the next. The equivalent requirement in ISO 9703-2 was defined as the time from
the start of the first group to the start of the next. In practice, this time
could be unacceptably short. Therefore, few MANUFACTURERS actually complied with this ISO 9703-2
requirement. Instead, they chose the interpretation that is now used in this
collateral standard. The intent of the pause was that the first group of PULSES would attract the OPERATOR'S attention, and the second group would emphasize the
importance of the ALARM CONDITION and aid in identifying the source of the ALARM CONDITION once the OPERATOR'S attention had been gained.
ü
d) A greater range of INTERBURST INTERVALS is permitted. The existing requirement in
ISO 9703-2 is not suitable for ALARM SYSTEMS that are unattended by the OPERATOR in NORMAL USE.
û
Selection of the most appropriate INTERBURST
INTERVAL requires RISK ANALYSIS and careful consideration of the clinical
requirement for the ALARM CONDITION in its intended environment of use. Short
INTERBURST
INTERVALS can result
in noise pollution and impair communication among OPERATORS or other personnel who are trying to
address the problem, and are inappropriate for ALARM SYSTEMS that are always attended by the OPERATOR in
קטע
זה הוא העתק
של קטע קודם
Factors to consider include:
– whether
the ALARM SYSTEM is intended to be always attended by the OPERATOR in NORMAL USE. In this case a longer INTERBURST
INTERVAL is
appropriate;
EXAMPLE Anesthesia machines.
– the
kind of equipment involved;
EXAMPLE An enteral feeding pump should have a longer INTERBURST
INTERVAL than a critical care ventilator.
השיקול הוא
של מצב
החירום, ולא
של סוג המכשיר
– whether
the ALARM SYSTEM is connected to a remote DISTRIBUTED ALARM SYSTEM, e.g. a central monitoring system. An ALARM SYSTEM that is not so connected (standalone
equipment) should consider a shorter INTERBURST INTERVAL, in order to facilitate identification;
האם יש
כאן טענה
שבמערכת
מבוזרת אין
צורך לזהות את
החולה? אולי הכוונה
היא שבמערכת
שכוללת זיהוי
אוטומטי של
החולה, ניתן
להגדיל את
המרווחים?
- the presence and effectiveness of
additional or alternative notification systems (secondary visual ALARM SIGNALS,
vibratory ALARM SIGNALS, ALARM SIGNAL lights in hallways, alarm paging systems,
etc). Effective alternative generation of ALARM SIGNALS will permit longer INTERBURST
INTERVALS.
זה לא
בשליטת היצרן.
מתקבל הרושם
שכדאי לפצל את
כל המסמך לשני
חלקים: הנחיות
ליצרן
והנחיות
ללקוח
ü
e) HIGH PRIORITY auditory ALARM SIGNAL PULSES should be “faster” than MEDIUM PRIORITY auditory ALARM SIGNAL PULSES to ensure that they are perceived as
being more urgent. Hence, the requirement that the effective PULSE duration for HIGH PRIORITY ALARM
SIGNALS is less than
that for MEDIUM PRIORITY.
ü
f) The LOW PRIORITY auditory ALARM SIGNAL is optional, but if present can comprise
one or two PULSES.
It should be relatively unobtrusive and perceived as less urgent than a MEDIUM PRIORITY
ALARM SIGNAL.
ü
g) Pitch is now permitted to rise and fall during a BURST. ISO 9703-2 required that changes in
pitch proceed in one direction only. The committee considered this to be
without safety advantage and excessively design restrictive.
ü
h) The ISO 9703-2 requirement for the presence of four
harmonics has been slightly modified. Reflections and standing waves from pure
sine wave auditory signals can make it very difficult to find where they are
coming from. Ensuring that four or more audible harmonics are present in an
auditory ALARM SIGNAL enhances spatial localization. These harmonics should be
neither so soft as to be inaudible nor so loud as to be excessively dominant.
Because tight control of harmonic content can be extremely difficult in simple
systems, a value of plus or minus 15 dB (relative sound pressure level) was
chosen as a reasonably achievable goal. Decibels were used to express the ratio
between the sound pressure level of the fundamental and the sound pressure
level of the harmonics because they are commonly used to describe relative
sound pressure levels. The choice of harmonic content is very flexible and
permits sounds of very different tonal quality to be created.
i) Fall time for pulses is now less
restrictive. It can be any duration that does not overlap the next pulse.
זה
לא מספיק טוב.
צריך להגדיר
מרווח
מינימום, והוא
צריך להיות
גדול יחסית
בכדי להשיג
אפקט של תחושת
סכנה.
ü
In contrast, ISO 9703-2 sounds were required to have the
same fall time as rise time. The committee found this to be excessively design
restrictive.
? Manufacturers are now
permitted to create sounds with more distinctive envelopes (e.g., bell-like
decays or reverberation effects).
לא בטוח
שזה טוב. צריך לבדוק
ü
RISE TIME for PULSES is specified as 10 % to 20 % of PULSE duration. There is no significant change
from ISO 9703-2. More rapid RISE TIME can be intrusive and startling, but can express greater
urgency.
ü
There is no change in the PULSE frequency requirement. Spatial
localization is poor at low frequencies, so the lower limit for fundamental
frequency is set at 150 Hz. Hearing impairment from noise exposure or age
usually impairs perception of higher frequencies, so that to ensure that all
harmonics are audible, the upper limit for fundamental frequency is set at 1
000 Hz. MANUFACTURERS can choose any frequency they like from within this range.
Higher pitch is associated with greater urgency. [11]
ü
The difference in amplitude between any two PULSES in a BURST should not exceed 10 dB. Again, this
refers to a relative sound pressure level ratio (i.e., not an absolute volume
difference in dBA). This
requirement is unchanged from ISO 9703-2. It is easier to make all PULSES the same amplitude, but if the amplitude
of the early PULSES in a BURST is a little less than subsequent PULSES, it can be less startling.
ראוי שתכונה
זה תתבטא
בדרישות