As a mom who conditioned her kids to sleep with fans, I can appreciate the addiction to sound machines.
We’ve found only two downsides to the box fan concept: 1) when the power goes out during the night (usually resulting in a child or two bolting upright in bed because it’s too dark AND TOO QUIET!) and 2) when we travel. Going by car? In goes the fan. Not such an easy carry-on item, though.
Bear and T-man are slowly adjusting to sleeping no matter what the conditions, but there are still trouble spots. Thunderstorms. “Weird” noises coming from outside the window. Traveling somewhere with noisy footsteps overhead and banging doors. But hey, sleeping under all conditions is a skill one has to cultivate, especially before heading off to college.
RachRiot wrote about sleep and sound machines and the insane array of settings available on these things. Her description of a slightly non-scientific study on these things is, indeed, a riot to read. Take a few moments to enjoy it yourself.
Riddle from the Middle 