A lot of parents believe in the "white noise" and it does seem to work for a lot of babies, but (this is not scientific by any means) what I have noticed with other kids we know closely is that if you start them with white noise they will continue to need it as they grow older and without it they are not as good of sleepers. So it seems to create a dependency. I know opinions like this could be argued with a lot of baby topics (food, play, milk, etc.), but the white noise is the only one that I have seen repeatedly hold up.
We were explicitly taught in pre-natal class that babies have to learn anew how to go to sleep once they're out of the womb, it's not something that's inborn.
For example, we were told it's hugely important to lay your baby down in their cribs as they're drifting off to sleep, but still just slightly awake, so they build the association between crib and going to sleep; if you only lay them down after they're asleep, this tends to have repercussions (e.g. because of the lack of the association, you're not equipping your baby to be able to go back to sleep if they randomly wake up).
As I recall, there is actually a fair bit of research behind this, but admittedly it's been 6 yrs so I don't remember all the details.
White noise is helpful, but falls into the same type of category.
