This is only effective if the microphone and speakers (inverse wave) are where you are... such as on your head. And it depends on the microphone's ability to d

This is only effective if the microphone and speakers (inverse wave) are where you are... such as on your head. And it depends on the microphone's ability to detect VLF. Even then, the speakers probably don't do well generating 20Hz or lower. To make it even more challenging, because this is a subtle sensitivity issue, and because most of us don't have identical hearing in both ears, you can't just pipe in the same volume of inverse wave to both ears. It's a really hard problem to solve. Plus it's not very comfortable trying to sleep with big headphones on; and nighttime is the worst time for this problem.