NFPA 72: 2010 the Chapter 29 requirements for household applications, specifically for those with mild-to-severe hearing loss, call for audible notification appliances that produce a low frequency 520 Hz sound. For those with profound hearing loss, the requirements include tactile notification appliances (such as a bed shaker) in addition to high-intensity visible notification appliances. Sleeping areas for those with mild-to-severe hearing loss have to use an audible notification appliance that produces a sound wave with a low fundamental frequency of 520 Hz.
In response to the changes in NFPA 72 for low frequency smoke and fire alarms in sleeping rooms, NFPA 720, The Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment, likewise adopted new provisions for the hard-of-hearing and profoundly deaf communities. NFPA 720: 2012 has identical provisions to those in NFPA 72: 2010 for notification appliances connected to a protected premises system. The effective compliance date is January 1, 2015.
The 2015 edition of NFPA 720 is expected to have identical provisions to those in NFPA 72: 2013. These provisions in NFPA 720 are intended to provide the same protection from CO hazards for hard-of-hearing and deaf individuals as NFPA 72 provides to these same individuals from smoke and fire.
Adaptation of these codes vary throughout the U.S. Follow manufacturer instructions and your local building/code regulations for the use and installation of any audible visible notification devices.
To accommodate these code updates, fire and life safety manufacturers continue to develop innovative solutions. There are now sounders and sounder strobes that provide the required low-frequency square wave tone. Some of these new devices are dual listed for wall- or ceiling-mount installations and are compatible with systems with proprietary synchronization protocol.