Wiktionary
silent alarms
n. (silent alarm English)
Usage examples of "silent alarms".
The now-silent alarms hadn't informed him of anything that he couldn't discern by other means.
Incorrect sequence will automatically reset it to an alternate combination and code, while triggering silent alarms in all or any of five selected locations.
The sudden and somewhat loud scrape of the bed set off silent alarms within Cadderly.
Could be silent alarms, she told herself, but if he's dismissed the servants for the night he'll have to come up here his own self, and I can handle that, easy.