Awakening of Sleeping People: A Decade of Research

The results of over a decade of research at Victoria University on the effectiveness of various smoke alarm signals for awakening sleeping people are presented and compared. The results show that the signal level (sound volume, light intensity, etc.) and the type of sound or signal affect the probability of people being woken up by an alarm. The 520 Hz square wave sound was the most effective of the sounds tested, waking most (often all) of the participants. The smoke alarms currently used in Australia and the USA emit sounds of about 3,100 Hz. Many participants did not wake up to such tones even when very loud at the pillow (95 dBA). In all groups tested the high-pitched sound was the worst and in most, notably children, young adults (sober and 0.05 BAC) and older adults, it was much worse than the 520 Hz square wave signal. In adults with hearing loss it was more than seven times as effective as the current signal and more effective than the bed and pillow shakers. Strobe lights were found to have very poor waking effectiveness. A voice alarm was quite effective for younger age groups but not for older adults. The voice alarm was also found to have real problems in waking participants with limited English. It is recommended that the 520 Hz square wave sound in the T-3 pattern be adopted as a replacement for the current smoke alarm sound.