Binaural beats have been shown to shift brain states, though quality peer-reviewed data is limited.

“Binaural beats, as their name suggests, involve playing one frequency of sound to one ear and a different frequency of sound to the other ear. And the idea is that the brain will take those two frequencies of sound. And because the pathways that bring information from the ears into the brain eventually cross over-- they actually share that information with both sides of the brain-- that the brain will average that information and come up with a sort of intermediate frequency. And the rationale is that those intermediate frequencies place the brain into a state that is better for learning.”