What are binaural beats?
When you hear two tones, one in each ear, that are slightly different in frequency, your brain processes a beat at the difference of the frequencies. This is called a binaural beat.
Here’s an example:
Let’s say you’re listening to a sound in your left ear that’s at a frequency of 132 Hertz (Hz). And in your right ear, you’re listening to a sound that’s at a frequency of 121 Hz. Your brain, however, gradually falls into synchrony with the difference — or 11 Hz. Instead of hearing two different tones, you instead hear a tone at 11 Hz (in addition to the two tones given to each ear).
Binaural beats are considered auditory illusions. For a binaural beat to work, the two tones have to have frequencies less than 1000 Hz, and the difference between the two tones can’t be more than 30 Hz. The tones also have to be listened to separately, one through each ear. Binaural beats have been explored in music and are sometimes used to help tune instruments, such as pianos and organs. More recently, they have been connected to potential health benefits.