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When was the last time you checked your home smoke alarm? Does it work? Does it have a good battery? Is it located in the best place of your house? A properly installed smoke alarm can save your life in the event of a fire.
But smoke alarms do not always awaken everyone and being asleep during a fire increases the risk of death. Children are especially difficult to wake up from the sound of a traditional smoke alarm. A new study suggests a more effective alarm for kids: a mother's voice!
Researchers tested the ability of a traditional tone smoke alarm and the sound of a mother's voice to wake up children from stage 4 sleep. The mothers of 24 children (6-12 years old) recorded a voice alarm with their child's first name such as "Sam! Sam! Wake up! Get out of bed! Leave the room!" Both the traditional tone alarm and the voice alarm were set to play at 100 decibels.
The children slept in a sleep laboratory with electrodes attached to their heads to record brain activity, muscle activity and eye movements. Once the children were asleep and had been in the first period of stage 4 sleep for five minutes, one of the alarms went off. The time it took the children to wake up and get out of the room (an escape) was recorded. The kids were then brought back to bed and allowed to fall asleep again. When the kids entered stage 4 sleep again, the other alarm was sounded and the time to wake up and escape were recorded.
Of the 24 children:
The voice alarm woke up the children in an average (median) of 20 seconds and 20 of these children escaped within 5 minutes. The children were awakened by the tone alarm in an average of 180 seconds and only 9 of them escaped within 5 minutes.
Older kids were more likely to wake up to the tone alarm. Only 2 of 10 children younger than 9 years were awakened by the tone alarm, but 12 of 14 children older than 9 years woke up to the tone alarm
This experiment demonstrates that voice alarms are more effective than tone alarms in waking up children from stage 4 sleep. What makes the voice alarm more effective is still unknown. It may be that the sound of the child's name or the familiar sound of the mother's voice is the important characteristic of the alarm. Alternatively, the frequency of a human voice may be the important factor. Future experiments that compare a mother's voice to that of an actor's may reveal some answers.
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