Comparison of the Effectiveness of Different Fire Notification Signals in Sleeping Older Adults

No previous research has investigated the responsiveness of older adults (65–85 years) to different emergency fire signals during sleep. In this study the auditory arousal thresholds (AAT) of 45 older adults were compared across four signals; the high pitched T-3 (as in current US smoke alarms), a mixed frequency T-3 (500–2500 Hz), a 500 Hz T-3 and a male voice. Participants were carefully screened, including for hearing, and awoken from deep sleep in a repeated measures design. Sounds increased progressively in volume until awakening occurred. It was found that the median AAT for the most effective signal, the mixed frequency T-3, was 20 dBA lower than the median AAT of the least effective signal, the current US high frequency smoke alarm signal. This finding is consistent with previous research, where the high pitched signal required a significantly louder volume than alternatives to wake sleepers of different ages, including children. Those aged over 75 years are especially at risk for sleeping through high pitched signals, probably due to the normal age-related decline in the ability to hear high pitched sounds. The minimum pillow volume of 75 dBA is inadequate for those over 75 years if a 3000 Hz notification signal is used. It is recommended that the high frequency signal currently found in smoke alarms be replaced by an alternative signal that performs significantly better in awakening most of the adult population, once the nature of the best signal has been determined.