I heard today about a new product that claims to be a more effective smoke/fire alarm. Instead of a siren, the alarm is a recorded voice. The idea is that when little kids wake up to an alarm, they are disoriented and confused. To hear specific instructions coming from their mom's voice is supposed to be helpful. The recording can be more than just "wake up." It can have detailed instructions like "There is a fire!! Get up and go out the back door right away!!!"
But I am conflicted on whether this is really better. I think that from a pure sensory salience perspective, there is not way that a voice is as loud or alarming as a siren. Also, the mom's voice is a common thing, so they won't instinctively associate it with an emergency. If they are sleeping, they may not hear enough of the voice to know it is the fire alarm. Also, as early as 10 years old, I am sure kids are trained to ignore their mom's voice waking them up: "Mom, I don't want to go to school today."
So the tradeoff is that a siren is better to wake them up and the voice is better to remind them of where to go. So which is more likely, that they fail to wake up or that they panic and forget where to go? I don't know this answer, but I suspect that the designers did not do the study to find out either. They guessed that this would be better and the lives of thousands of children will depend on them being correct. I hope they are.