Hearing Impaired Smoke Detectors

People who are hard-of-hearing may rely on auditory, visual, or tactile alarms in a fire emergency, and US standards require strobe lights in hotel bedrooms to provide emergency notification for people with hearing loss. This is the first study to compare the waking effectiveness of a variety of auditory (beeps), tactile (bed and pillow shakers), and visual (strobe lights) signals at a range of intensities.
The 2010 edition of NFPA 72(r) National Fire Alarm Code includes a provision that will require use of a low-frequency (520 Hz) square-wave signal for fire alarms installed in residential bedrooms of those with mild to severe hearing loss by January 2010, and in all commercial sleeping rooms by January 2014. This sound is a much lower frequency than the 3100 Hz pure tone sound of current smoke alarms and has been proven most effective at waking people up during a fire. With as many as 70 million Americans(1) having high-frequency hearing loss, this is a significant step to address a critical safety issue.

Fire alarm signal studies(2) commissioned by the U.S. Fire Administration and the Fire Protection Research Foundation, an affiliate of NFPA, demonstrated that a 520 Hz square-wave signal is proven to be most effective at waking people with hearing loss, heavy sleepers, older adults and children -- waking 92 to 96 percent of these individuals. The low-frequency signal was 63 to 69 percent more effective at waking children, heavy sleepers and people with hearing loss than current high-pitched alarms.
(1) Based on Johns Hopkins study published in Archives of Internal Medicine July 2008; and Cruickshanks et. al. Beaver Dam study published in American Journal of Epidemiology, 1998.
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