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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.

Binaural beats are said to provide many of the same benefits as meditation: lower stress, increase focus, aid with sleep and relaxation, boost mood, assist with pain management, and foster creativity. However, some of these claims are preliminary or not yet supported by scientific evidence.

How Do Binaural Beats Work?
Woman studying with binaural beats. LightField Studios/Shutterstock

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.

Delta waves (0.5-4 Hz) signify a state of deep sleep.

A binaural beat with a frequency between 4 and 7 Hz, for example, is more likely to align with theta brain waves, promoting sleep and relaxation.

What is entrainment?

Some evidence suggests that the tone being perceived can alter brain waves through a process called entrainment, in which brain waves align themselves to an outside beat or frequency. Since different brain wave patterns are associated with certain states of mind, from relaxed to anxious to productive, binaural beats have been theorized to impact mood, focus, and sleep by altering brain waves. As a result, the phenomenon has gained popularity in recent years as a potential therapy for anxietyinsomniaconcentration difficulties, and more.

How effective are binaural beats?

Though evidence for the efficacy of binaural beats remains preliminary, mixed, and based mainly on small studies, most experts agree that the risk of side effects is low. Many apps, podcasts, and other online services provide free access to binaural beats—often in conjunction with guided meditations, music, or other auditory stimuli intended to promote relaxation or focus.

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The Potential Benefits of Binaural Beats

Binaural beats, when tuned to an adequate frequency, are theorized to encourage the brain to gradually transition from a more alert, higher-frequency state into a slower, more relaxed one. Some small studies have supported this theory, while others have found evidence that the changes in brainwave patterns may also trigger hormonal changes—including increased levels of melatonin and DHEA and decreased cortisol levels. People who use binaural beats may report feeling more relaxed, seeing improvements in mood and motivation, experiencing increased focus and lower anxiety, and sleeping better.

Can binaural beats help with sleep?

Perhaps the best-known use of binaural beats is as a treatment for insomnia, a sleep disorder that affects large numbers of people, which can drastically decrease quality of life and may have a ripple effect on productivity, mood, and personal relationships. During sleep, the brain generates different types of brain waves, depending on the sleep stage and the current level of mental arousal. Low-frequency theta and delta brain waves are associated with relaxation and deep sleep. Binaural beats could help you sleep better by creating shifts toward theta and delta-type brain waves.

Can binaural beats reduce depression?

For those who are suffering from depression, listening to music and/or binaural beats in the frequency range corresponding with alpha, theta, or delta brain waves can provide some relief. Binaural beats music could reduce depression for some people, but most depressed individuals will get better results if they try binaural beats in addition to traditional therapy. If any negative side effects are noticed, it’s best to stop and consult a therapist or physician.   

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