When two tones of slightly different frequencies are played in separate ears simultaneously (usually through headphones), the human brain perceives the creation of a new, third tone, whose frequency is equivalent to the difference between the two tones being played. This auditory illusion is called a binaural beat. For example, if a person hears a tone of 405 Hz in one ear and a tone of 415 Hz in the other, they would be hearing a binaural beat with a frequency of 10 Hz.
How Do Binaural Beats Work?
In order to produce a binaural beat, the two tones sounded in the ears must both have frequencies below 1,500 Hz with a difference of no greater than 40 Hz between them. The effects of the binaural beat will depend on its frequency and the corresponding brain wave:
Beta waves (13-16 Hz) occur when we are awake and alert.
Alpha waves (8-12 Hz) happen when we are relaxed with eyes closed, as in meditation .
Theta waves (4-7 Hz) are common in the lighter stages of sleep or the transition from waking to sleeping .
Explore More About Binaural Beats
For a comprehensive understanding of binaural beats, read our complete guide: