Binaural beats are auditory illusions created in the brain when two different pure frequencies are played in the left and right ears; the frequencies must have a difference between them of less than 40Hz and both be lower than 1500Hz. The result is that the brain hears a “wobble” and interprets it as a singular frequency at the difference between the two played tones. People report many benefits to listening to binaural beats, including stress and anxiety reduction, an increase in focus and concentration, relief from pain, and deeper sleep or meditative states.