COLUMBUS, Ohio (AP) -- Children in deep sleep awoke to recordings of their mothers' voices -- calling them by name and ordering them out of their bedrooms -- even if they slept through the beeping sound a smoke alarm makes, according to a small study.

The study reaffirms previous research that shows what works for adults doesn't always work for children, said Dr. Gary Smith, one of the co-authors.

"Clearly, the strategy that has been tried and true and used for years ... fails miserably for children," said Smith, director of the Center for Injury Research and Policy at Columbus Children's Hospital.

The study of 24 children ages 6 to 12 found that 23 awoke to the recorded voice of their mother saying "(Child's first name)! (Child's first name)! Wake up! Get out of bed! Leave the room!" Fourteen of the children also awoke to the traditional tone alarm. One child didn't wake up to either.

The children who woke up to the voice did so at a median time of 20 seconds, compared with three minutes for those who woke up to the tone, according to the study by Columbus Children's Hospital researchers being released Monday in Pediatrics.

Both alarms were created using a large speaker and sounds measuring 100 decibels, about four times louder than levels used in standard home alarms, Smith said.

The next step, he said, is to determine why children responded to the voice alarm differently, whether they were responding to their names, their mothers' voices or the frequency at which the sound was delivered, which was lower than the frequency of a beeping alarm.

Nancy Baron of Columbus said her daughter Maddie, who was 8 at the time of the study, awoke to the voice alarm in 15 to 20 seconds but slept through the tone alarm, while neither alarm woke her son Rhys, who was 7.

"I was totally shocked," Baron said. "It was actually a little frightening to think what would happen if this was real."

Funding for the study came from a grant from the Ohio Department of Public Safety's Division of Emergency Medical Services and the Ohio Emergency Medical Services Board.

A safety expert said the study was a start.

"We have a piece of the puzzle now and we're really happy someone has taken up this research and we hope it moves forward," said John Drengenberg, manager of consumer affairs for Underwriters Laboratories Inc., an independent organization that certifies safety for consumer products.

The U.S. Fire Administration estimates that 3,300 fatal fires killed 3,380 people (not including firefighters) in 2005, with 14 percent of victims younger than 10. Smoke alarms were not present in 42 percent of residential fatal fires; alarms did not operate in 21 percent.

Drengenberg said statistics show that no children have died because they didn't wake up to a smoke alarm.

"What we do know is parents instinctively ... will go to a child's room and grab a child out of the crib or out of the bed," he said.