I used to have a TV which had a setting that would turn it on and go to a specific channel at a set time. I would set it to go to the history channel every morning because they would play random stuff from their archives in the morning, so it was impossible to get fully desensitized. One day I'd wake up to the history of candy, the next day it'd be the history of stealth aircraft, the next day it'd be the history of the klan (that was not the best way to start the day).
The alarm app I use allows for playlists to be used as the alarm, and I have a different one set for every day of the week. It's not quite as effective at preventing me from tuning it out, but that's balanced out by the fact that I have to solve puzzles and math problems to turn it off. Combined with an alarm clock that has a light that slowly turns on in a simulated sunrise and it's pretty effective.
I put my alarm as birds chirping for a while. The problem was that I couldn't sleep in any longer on weekends, because the birds chirping outside would wake me up.
Record your child when they are young... There is some internal biological thing going on. My daughter could wake me up out of a slumber that a freight train running by my pillow would not.
I think even an infant crying would get most people, even if childless.