The Lifetone Fire Alarm and Clock with Smoke Detector uses a patented sensor that works by hearing existing smoke alarms then broadcasting a nearly impossible-to-ignore 520HZ sound to wake heavy sleepers and people with hearing loss. If the loud noise doesn’t work, the alarm can actually shake the bed. The unit will detect T3 alarms through in multi-story homes, even through walls and closed doors.
By the way, it also functions as a standard alarm clock.
The Lifetone Bedside Fire Alarm and Clock sells for about $180 US on Amazon.