Robert Monroe and Hemi Sync.

Another form of binaural beats is called Hemi Sync. Here's a bit about that;

Robert Monroe, the founder of The Monroe Institute, dedicated 40 years of his life to developing brainwave entrainment technology. In fact, it was during tests of his “white noise” creations in the 1950s that he began to have out of body experiences – against his will!
Monroe had tapped into something critical: that brainwaves (and therefore different levels of consciousness) can be guided by external sound frequencies.
Monroe wrote three fascinating books about his out of body experiences while running The Monroe Institute – arguably the world’s most famous research organization into human consciousness. It’s from this platform that Monroe and his team at the Institute developed the brainwave guidance technology known as Hemi Sync.