ISO/IEC 60601-1-8, Patterson and compromise alarms in medical equipment
Sample Alarm Sounds - Sirens, buzzers and other sounds
This page by Chris Thompson 27 July 2000
Comments to Frank Block or Chris Thompson.
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Clicking on the blue underlined link should play the sound. All sounds are 8bit 22kHz mono uncompressed files in Windows 'wav' format. File size varies between 30 and 120 kiloBytes. Time lags when playing sounds may be reduced by downloading the whole sound set as a web archive, then running the page as a local file on your computer.
1. 60601-1-8 type sounds
1.1 Urgency encoded
Low Alarm
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Medium Alarm
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High Alarm*
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Notes
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Not specified
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C4 C4 C4
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C4 C4 C4 - C4 C4
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Fixed pitch;
traditional (usual )9703 sound.
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1.2 Combined category and urgency encoding (Apendix HHH; Block/Hakkila/Thompson)
Category
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Medium Alarm
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High Alarm*
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Notes
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General
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C4 C4 C4
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C4 C4 C4 - C4 C4
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Fixed pitch; complies with JWG standard;
traditional (usual )9703 sound.
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Oxygen
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C5 B4 A4
OX-Y-GEN
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C5 B4 A4 - G4 F4
OX-Y-GEN A-LARM
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Slowly falling pitches, falling pitch of an oximeter;
Top of a major scale;
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Ventilation
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C4 A4 F4
VEN-TI-LATE;
RISE AND FALL
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C4 A4 F4 - A4 F4
VEN-TI-LA-TI-ON;
VEN-TI-LATE A-LARM
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Old "NBC Chime", rise and fall of the lungs
Inverted Major Chord
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Cardio-vascular
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C4 E4 G4
CAR-DI-AC
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C4 E4 G4 - G4 C5
CAR-DI-AC A-LARM
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Trumpet Call, Call to arms;
Major chord.
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Temperature or Delivery of Energy
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C4 D4 E4
TEM-P’RA-TURE
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C4 D4 E4 - F4 G4
TEM-P’RA-TURE A-LARM
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Slowly rising pitches; slow increase in temperature
Bottom of a major scale.
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Drug Delivery
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C5 D4 G4
IN-FUS-ION
DRUG-OR-FLUID
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C5 D4 G4 - C5 D4
IN-FUS-ION A-LARM
DRUG-OR-FLUID A-LARM
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Drops of an infusion falling and "splashing" back up Jazz chord inverted 9th
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Artificial Perfusion
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C4 F#4 C4
PER-FU-SION
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C4 F#4 C4 - C4 F#4
PER-FU-SION A-LARM
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Artificial sound, "Yo-ee-oh" of the Munchkins in "The Wizard of Oz"; Tri-tone.
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Power Failure
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C5 C4 C4
POW-ER FAIL
GO-ING DOWN
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C5 C4 C4 - C5 C4
POW-ER DOWN A-LARM
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Falling pitch as when the power has run down on an old Victrola
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Low alarm
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E4 C4 (slower)
IN-FO; MESS-AGE
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Ding-dong; doorbell or hostess call.
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* all high alarm bursts comprise the same 5 note pattern played twice, separated by 2 seconds of silence - 10 pulses in all.
Notes:
1. The CD permits a wide range of pulse tone. Pulses of a musical nature are permissible but not demonstrated here. Variation in tonality between equipment is acceptable and probably desirable. The above examples were constructed as follows:
2. All bursts are fully compliant with the requirements of the CD. They were constructed using the following values, with requirements of CD in brackets:
** Absolute pulse amplitude will depend on your speaker volume. The CD requires amplitude of lower prioirty bursts to not exceed the amplitude of higher priority bursts. My choice of -3dB and -6dB for relative amplitude of medium and low is arbitrary. The first pulse of each burst is 80% of the amplitude of all the other pulses, which are equal in amplitude. The CD permits up to 10dB of pulse amplitude variability from pulse to pulse. Gradually increasing pulse amplitude during a burst may be desirable to reduce intrusiveness and avoid unwanted startle responses.
** The CD requirement for fall time is any time that does not overlap the start of the next pulse. Actual fall times are arbitrary, however longer fall times are associated with lesser perceived urgency. Figures in brackets are possible fall times that meet requirements for these pulses as specified in the CD.
Graphical representations of alarm bursts used in these examples (same time scale):
(a) high priority
(b) medium priority
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2. Patterson Sounds
Patterson designed alarm sounds for the British Government. These examples were designed for the working group to demonstrate both urgency encoding and category encoding. They were digised from a tape recording.
2.1 Urgency encoding:
Urgency
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Description and notes
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Low
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Two pulses, falling pitch
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Medium
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Four pulses, rising pitch
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High
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Two identical bursts of 6 pulses each. Each burst comprises the same four notes of the medium alarm (though louder and at higher pitch) with two additional 'attention' pulses appended.
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2.2 Combined category and urgency encoding:
Six categories were defined, each with their own specific sound pattern. Greater urgency is indicated by repeating the same melody twice, and at higher pitch, faster tempo and higher amplitude. Pulse amplitude increases gradually during a burst to avoid startle reactions.
The logic of using the same sound twice is that fewer sounds must be learned. Also it is intuitively obvious that "FIRE!, FIRE!" is of greater ugency than 'fire' or 'hello'.
3. Compromise - "Chris Thompson" - Alarm Sounds
These sounds are both urgency and category encoded.
They incorporate Patterson's concept of using the same base category sound repeated twice for high priority sounds, yet are based on the 60601-1-8 melodies. The number of categories have been rationalised to avoid confusion and enhance ease of learning (temperature and perfusion do not exist; they could use the general sound or perfusion could be mapped to a cardiac sound). I have addtionally included a 'very high priority' version to show how speed, rise time and volume can additionally emphasise urgency. In urgent situations. 2.1 Urgency encoding:
Note how the high priority alarms are annunciated in much less time than the existing 60601-1-8 sounds. For example, my 'very high' alarm sound takes only 1.3 seconds to fully annunciate, whereas an equivalent 60601-1-8 high alarm sound takes 4.6 seconds. In an emergency, when multiple alarms happen at once, brief alarms are less likely to overlap with others, wherehas multiple longer alarms will result in a cacophany - like 'everyone shouting at once'.
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