Annex D (informative)
Guidance for auditory ALARM
SIGNALS
D.1 General considerations
ü
Parameters
that affect the perceived urgency of a BURST of sound include the
inter-PULSE interval, the number of repeating BURSTS,
the rhythm of the PULSES in the BURST, changes in intra-PULSE duration within a single BURST, the
pitch contour, pitch range and musical structure.
Table D.1 – Attributes of perceived urgency
מה עם
העוצמה?
D.2 Frequency range
ü
The
frequency range of an ALARM
SIGNAL should be between 200 Hz and 5 000 Hz.
The preferred range is between 500 Hz and 3 000 Hz. If the ALARM SIGNAL is required to be audible at a long distance, such as a large ward, the
frequency should be below 1 000 Hz. If the ALARM SIGNAL is required to be
heard around obstacles or through partitions, the frequency should be below 500
Hz. The selected frequency band should differ from the most intense background
frequencies in the equipment’s expected environment of use.
D.3 Continuous auditory ALARM SIGNALS and INFORMATION SIGNALS
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The use
of continuous tones for ALARM
SIGNALS or INFORMATION SIGNALS should be
discouraged as they impede communications between persons, are annoying and
provoke a startle reflex. Continuous tones often cause an OPERATOR to
invoke the ALARM OFF state of ALARM
SYSTEMS.
D.4 Harmonics, timbre, FALL TIME
ü
Despite
the restrictive nature of the sound specification in this collateral standard,
varying the harmonic content and PULSE FALL TIME, while retaining
the distinctive nature of the melody, can create distinctive ALARM SIGNALS. This permits a subtle degree of equipment differentiation, which an OPERATOR can
find advantageous.
ü
Sounds
with odd harmonics (3,5,7,9,11) have a harsh quality, even
harmonics give a church organ type of sound, and combining odd and even results
in an oboe-like quality.
עכשיו, על מה ממליצים? להתריע למשתמשים או להרגיע את החולים?
ממליצים על צליל שנותן את ההתראה ועם זאת לא מעצבן במידה שגורמת למשתמש לסגור את האזעקה כותבי התקן מצאו צליל רצוף כבלתי נעים ומעצבן.