Are Binaural Beats Real Science? Exploring the Auditory Phenomenon
How do you relax before you fall asleep? Maybe you follow a guided meditation, or perhaps you listen to a podcast or peaceful music. Binaural beats aren’t a music genre. They are an auditory phenomenon created by your brain in response to hearing specific tones in each ear.
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.
Binaural beats are not a sound but an auditory phenomenon that occurs when listening to two different frequencies at once. If you listen to two tones, each at a different frequency and each in a different ear, your brain creates an additional tone you can hear. This third tone is called a binaural beat. For example, if you listen to one tone at 300 hertz (Hz) and the other tone at 310 Hz, the binaural beat you hear is at 10 Hz.
This creation of a third sound is caused by the same part of the brain that helps you determine the location of a sound. To hear the binaural beat, you must have sound coming in each ear. When binaural beats are sustained over a period of time, they can synchronize with your brain waves. Binaural beats can be created at different frequencies.
Diagram illustrating how binaural beats are created by presenting different frequencies to each ear.
Brainwave Patterns and Binaural Beats
The brainwave entrainment hypothesis assumes that external stimulation at a certain frequency leads to the brain’s electrocortical activity oscillating at the same frequency, providing the basis for research on the effects of binaural beat stimulation on cognitive and affective states. What makes the possibility of brainwave entrainment (BWE) interesting for psychological research is that specific frequency bands of the human EEG are associated with different physiological and psychological states [33]. The commonly held assumption is that BWE may, thus, be a method to induce specific physiological and psychological states through stimulation within particular frequency bands [15].
Binaural beats can be created at different frequencies. Different frequencies of brain waves are associated with different states of mind:
- Delta (δ) pattern: The slowest brain waves are delta waves. These waves have a frequency under 4 Hz. As you transition into deeper sleep stages, your brain switches from theta waves to delta waves. Dreaming can occur.
- Theta (θ) pattern: During stage one of sleep, which is the lightest stage of sleep, your brain produces theta waves at a frequency between 4 Hz and 8 Hz. Theta waves are also associated with drowsiness and meditation.
- Alpha (α) pattern: Ranging between 8 Hz and 13 Hz, alpha waves indicate a relaxed and restful mind.
- Beta (β) pattern: Beta waves range between 13 Hz and 30 Hz. These waves in the brain are linked to an active and alert mind. This type of brain activity is associated with alertness, concentration, and problem solving. Higher levels of beta waves are also associated with anxiety.
Research on Binaural Beats
Research on binaural beats started as early as 1839, when the phenomenon was first described by H. W. Dove [25]. However, given that it is a perceptual response to stimuli which are artificially generated and do not occur in natural settings, binaural beats were dismissed as a mere curiosity for more than a century. Scientific interest in binaural beats has been rekindled only much later when the results from early empirical studies were systematically integrated by Oster [9]. Not only did he describe the phenomenon in more detail, he also highlighted the potential relevance of binaural beat stimulation for practical use.
Within this field of study, effects on cognition, emotion, as well as certain concomitant physiological changes are investigated [31, 32]. Effects of binaural beat stimulation have, consequently, been investigated with respect to a variety of psychological phenomena associated with specific EEG frequency bands, such as aspects of cognitive processing [31, 34, 35], affective states [31, 36, 37], mood [1, 38, 39], pain perception [40, 41], meditation and relaxation [42, 43], mind wandering [44, 45], or creativity [46].
Preliminary research suggests that binaural beats can help you sleep better. A study using binaural beats at a delta frequency of 3 Hz showed that these beats induced delta activity in the brain. As a result, the use of binaural beats lengthened stage three sleep. Other small studies indicate the potential of binaural beats for better sleep, less sleepiness, and increased ease of waking up.
Binaural beats, like monaural beats, fall into the range of auditory modulated tones, which are frequently used in basic acoustic research as well as in clinical diagnostics [19]. Any auditory stimulation using repetitive or modulated tones elicits a specific neural response pattern that can be measured by electroencephalography (EEG) or magnetoencephalography (MEG) [19]. Neural responses are detectable, for example, as auditory steady state responses (ASSRs) [20] or auditory frequency-following responses (FFRs), which both appear immediately after stimulus onset in the form of composite waves [21, 22]. ASSR and FFR can be functionally attributed to discrete stages of auditory processing and are, thus, both relevant for sound processing and hearing research [23].
The theoretical basis of psychological research on the effects of binaural beat stimulation is provided by the brainwave entrainment hypothesis [15] which suggests that auditory or visual stimulation at a specific frequency will lead the brain’s electrocortical activity to oscillate at the external signal’s frequency or at its multiples. For binaural beat stimulation, the brainwave entrainment hypothesis was corroborated primarily by empirical studies demonstrating time-locked ASSRs [4, 13, 24].
However, it is important to consider that some researchers have argued there is insufficient evidence linking binaural beats with lessened anxiety or improved sleep. At first glance, however, the available literature on brainwave entrainment effects due to binaural beat stimulation appears to be inconclusive at best. The results corroborate the impression of an overall inconsistency of empirical outcomes, with five studies reporting results in line with the brainwave entrainment hypothesis, eight studies reporting contradictory, and one mixed results. The methodological heterogeneity in this field of study ultimately limits the comparability of research outcomes.
Given that the theoretical basis of the applied studies on effects of binaural beat stimulation is the brainwave entrainment hypothesis [15], the fact that a considerable number of available basic research studies failed to demonstrate sound evidence for BWE [36, 37, 40, 42, 44-46] makes the results of those applied research endeavors highly questionable.
Conflicting findings regarding BWE can be attributed to a number of obvious problems in this field of research. First of all, the operationalization of entrainment effects in the human EEG is diverse, with some researchers considering the presence of time-locked responses in the auditory system (ASSR and FFR, respectively) as indicators of BWE [e.g., 1, 4, 52], while others focus on changes in EEG power measures (oscillatory activity) [5, 50, 51, 55].
Heterogeneity starts with the study samples, with most studies involving healthy adult populations [e.g., 2, 51, 55, 57], while others examine neurological samples [16, 64]. Another problem is related to the variety of frequencies used for binaural beat stimulation. This is of special importance since it is assumed that different frequency bands differ in their capacity to be entrained [52].
While research on potential psychological effects of binaural beat stimulation is based on the assumption of brainwave entrainment, the empirical basis for this presupposition is open to question given that neuroscientific results on BWE through binaural beat stimulation appear to be largely inconclusive.
How to Use Binaural Beats
If you decide to use binaural beats in hopes of improving sleep, there are numerous binaural beat tracks available online. You can also purchase CDs or audio files featuring binaural beats. Oftentimes, these tracks have white noise or other gentle sounds to help you relax. The length of binaural beat tracks vary.
When listening to binaural beats, make sure you have sound entering each ear. You can wear headphones or earbuds, whichever is more comfortable.
| Frequency Range (Hz) | Associated Brainwave | Potential Benefits |
|---|---|---|
| Under 4 | Delta (δ) | Deep sleep, relaxation |
| 4-8 | Theta (θ) | Drowsiness, meditation |
| 8-13 | Alpha (α) | Relaxation, restfulness |
| 13-30 | Beta (β) | Alertness, concentration, problem-solving |
Table summarizing the relationship between binaural beat frequencies and associated brainwave states.
Potential Side Effects and Precautions
Currently, only a few negative side effects of using binaural beats have been reported. Some listeners report irritability or frustration while listening to the beats.
Exposure to sounds at or above 85 decibels (dB) can result in hearing loss. Examples of everyday sounds at that level or above are motorcycles, concerts, sporting events, and listening to music at full volume through headphones.