I have a lamp that will turn on and play bird noises over the course of half an hour (starting from almost nothing and coming to full intensity over the course of that half hour) and I suspect the mechanism is the same. I set it for half an hour before I actually think I need to be up though because of that window.
I have a lamp like that and the bird noise is about a 4 second, very obviously looped, loop. It's even more unbearable to be slowly woken up by that that just hit over the proverbial head with a loud normal alarm.
