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.


ü        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.