Umm, I think this requires multiple triggers?
One trigger that sets a variable like
my_alarm to true when you want the alarm to sound, the one playing the sound would have condition my_alarm and a third trigger would also have a condition my_alarm but would also have countdown of the time you want the alarm to sound (min, max, mid boxes)
and 'on activation' field would have
my_alarm=falseTrigger 1:
The trigger detecting East not present
Repeatedly
Condition: this && !(my_alarm)
On activation: my_alarm=true
Trigger 2 (sound):
size: 0/0
Repeatedly
Condition: my_alarm
Effect: alarm sound
Trigger 3
size: 0/0
Repeatedly
Min: (time in seconds) Max: (time in seconds) Mid: (time in seconds)
Condition: my_alarm
On Activation: my_alarm=false
That
should work, but no guarantees