The usability failure mode

Recommended protection

Validation

Sound disabled after resumption

The user might forget to re-enable the sound after the alarm condition is over

IEC 60601-1-8 (section 6.8.2) suggests that a reminder signal may be used, and warns from undesired changes in the settings of these signals.

Visual indication of disabled sound

The system should provide a visual indication that the sound alarm is disabled.

1. Set an alarm condition
2. Verify that the user responds
3. Wait until the alarm condition is over
4. Verify that the user notices that the alarm condition is disabled

Automatic sound enabling

Following a delay (of about 30 seconds?) after the alarm condition is over, the sound alarm should be automatically re-enabled. A test sound may be used to notify about the termination of the alarm condition, and the normal monitoring resumption.