The logic behind this strategy seems to be better applied for activities during theday, day, when one is awake, but I am wondering about other effects this type of exposure to repetitive sound while sleeping might have, similar to the snooze effect that is already demonstrated as being stressful to the mind and body.
When waking up in the morning and noticing that they slept through their set alarms, people get stressed and the next time they go to sleep they think that maybe placing the alarm clock, which today is mostly replaced by a smartphone, closer to their heads, even under the pillow, so that it's closer the the ear and maybe they will hear it better. This of course has no real effect on them actually reacting to the sound of the alarm and really waking up.
The body is most probably in some stage of deep sleep and the brain has the auditory system paralyzed to some degree or maybe involved in other functions of dreaming, because obviously hearing does not have much effect, in the sense that it does not complete its function of sending the audio signals to the brain or maybe the brain receives the signal but does not always react to the sound of the alarm. The question could be at this point if the brain perceives the sound. I am pretty sure that the cells in the ear, responsible for sound processing react. I remember seeing a documentary on how they work and they are passive and just react to different frequencies of sound and there are a whole range of such cells, called cills, that depending on their size react to different frequencies. So the sound gets sent to the brain and is transformed into electrical signal because sound is not something really voluntary. And you notice this sometimes when you dream and sounds in the surroundings, like TV, alarms and even peoples voices get slightly integrated into the dream.
I think the body has a way of dealing with sounds disturbing sleep and learns to ignore them in order to rest regardless of the intentions set by you using your mind. It is very important also what type of motivation lies behind needing to wake up. It could be, as it so often is, that you must wake up to go to work or school, which is in large an external set motivation which one internalizes to various degrees and becomes responsible in regards to it, and trains himself to respect hours when waking up.
It could also be that you want to wake up to do something for yourself or you are on a vacation and are more eager to explore new things and can barley sleep and are excited and wake up even before the alarm rings.
The scenario discussed here however is a repetitive one from Monday to Friday between 10:00-11:00 (falling asleep interval) p.m. and 3:00-8:00 a.m. (alarm ringing interval) the next day. The classic modern workweek sleep schedule of city people.