This weekend, we had the privilege of partnering with the Sugar Creek Fire Department in New Palestine for their annual safety fair.  The event sparked my interest in Fire Safety for the hearing impaired and after reviewing research I discovered traditional smoke alarms like the one in my home are not very effective at waking sleeping adults, even those with normal hearing.

Traditional alarms emit a high-frequency signal (3100Hz).  Most hearing impaired individuals have a high-frequency loss.  Children are even harder to arouse than adults, even if the child has normal hearing.  In one study, only 23% of kids were aroused within three minutes of alarm activation.  Three minutes is the critical time established for mortality/survival rate from a damaging fire.

Low frequency (520 Hz) signals produce better arousal rates but the consumer should know the size of the detector will increase.  Another interesting fact is the arousal rate improves when the alarm is paired with a vibrotactile device (bed shaker) instead of a visual alarm (strobe light).  My previously held assumption about recommending paired visual signals, even for those who meet the definition of “deaf” was wrong.

In conclusion, 520 Hz square wave alarms have demonstrated in research to be the most effective in waking a sleeping adult, especially when paired with vibrotactile (bed/pillow shaker) devices, at waking sleeping adults with hearing loss.

For more information, check with your local Fire Department or these online resources:

Beyond Hearing Aids

Harris Communication

Silent Call