Chicago ? Anna Marie Newson thought her family would be safe with smoke detectors in her home’s hallways and the bedrooms of her five children.

But the Milwaukee-area mother got an alarming wake-up call when the blaring detectors failed to rouse several of the children during an experiment done by local fire officials and a television news crew.

“We were outside and we could hear the alarms going off,” Newson said in an interview this week. “It’s kind of scary. At least now we know.”

Those results helped prompt a warning from safety specialists that it may take more than just the traditional siren-based alarms to awaken young children during a fire.

Proposed alternatives include recordings of parents’ voices, vibrating alarms or even flashing strobe lights, according to the Northbrook, Ill.-based Underwriters Laboratories, an independent organization that certifies safety for consumer products.

Government data show that from 1991 to 2000, there were more than 33,000 deaths from residential fires nationwide — 24 percent among children under 15, Underwriters Laboratories says.

Newson found she had to awaken several of her children, then aged 8 through 14, after eight minutes of blaring. Fire officials say less than two minutes is an optimal escape time.

Children younger than 10 spend as much as 30 percent of their slumber time in deep hard-to-rouse-from sleep, while adults spend as little as 10 percent of their slumber in deep sleep, said Dr. Stephen Sheldon, a sleep specialist at Chicago’s Children’s Memorial Hospital.

Children also are more likely to be disoriented and confused when awakened during the deep-sleep phase, he said.

“The amount of sound that’s required to awaken a child during middle childhood is enormous, much greater than currently available smoke alarms,” said Sheldon, who co-chaired the UL panel.