Since 2014, NFPA 72 requires that notification appliances installed in sleeping rooms provide a low frequency sounder signal. Research has shown that a low frequency 520 Hz signal is more effective at waking people with hearing loss and alcohol-impaired adults than a standard 3 kHz tone.
The 520 Hz signal must only be used in sleeping areas, not in common spaces such as hallways or lobbies.
What is a low frequency sounder?Low frequency sounders are devices that produce a low-frequency tone in order to awaken occupants who are asleep or hard of hearing. They are required in certain types of buildings, such as hotels, motels and apartments, that need to comply with NFPA 72, the National Fire Alarm and Signaling Code.
These requirements came about because research had shown that they are six times more effective than the standard 3kHz signal when it comes to waking sleeping occupants in fire situations. They are designed to alert individua…