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Binaural Beats for Behavior Modulation and Brainwave Entrainment

By Jasreen Singh

What are binaural beats?

Have you ever heard something that wasn’t actually there? Perhaps you were listening to an auditory illusion known as binaural beats.

A binaural beat occurs when two different tones at similar frequencies are played in each ear simultaneously. For example, if in one ear a tone is played at 330 cycles per second (Hz) and in the other ear a tone is played at 360 Hz, these two would cancel and the brain would perceive a leftover sound at a frequency of 30 Hz. This remaining beat is perceived by subcortical structures in the brain, specifically the superior olivary nuclei in the medulla where sound is processed. Binaural beat processing is an illusion of perception, as the tone being perceived is not one of the two tones presented to the ears. H.W. Dove was the first to understand the concept of binaural beats in 1839 (Chaieb et al., 2015). The binaural beat requires the integration of sounds from two different frequencies, and researchers are keen to understand its effects on attention, alleviation of anxiety, and related health benefits (Chiaeb et al., 2017).

A binaural beat occurs when two different tones at similar frequencies are played in each ear simultaneously.


To understand how a binaural beat works, it is important to understand brain waves. Brain waves occur when thousands of neurons fire in synchrony, creating rhythmic voltage patterns called oscillations. The different oscillations generated across the brain collectively fall into an identifiable brain wave pattern. A reference chart by researchers from the Western Sydney University school of Medicine in Australia (Buskila, Bellot, and Morley, 2019) outlines the common characteristics of brain waves and their localities in the brain. For example, delta waves occur at 1-4 Hz and are functional in slow wave sleep and deep REM sleep, decision-making, memory consolidation, concentration, motivation, and focused attention. Theta waves, which are seen at 4-10 Hz, are associated with REM sleep, selective attention, episodic memory, and word integration. Alpha waves, seen at 8-12 Hz, are connected to drowsiness, sensory function and perception, task engagement and the speed of working memory. Two additional brain waves are closely linked to cognitive functions: beta waves, found at 12-30 Hz, are seen in sensorimotor control, sensory processing amplification, top-down attention, and working memory allocation. Gamma waves, oscillating at greater than 30 Hz, are seen in focused attention, and spatial, working, and recognition memory.

 

Can binaural beats affect brain waves?
There is some amount of overlap between each type of brain wave and its relationship to cognition and neural function. Much research is still being done to understand how brain waves function and whether they can be modulated by an external stimulus such as a binaural beat.

Using binaural beats to synchronize our brain’s neuronal activity is a process known as neural entrainment, in which brain waves synchronize with an external stimulus. However, the use of binaural beats to induce neural entrainment is still controversial. In theory, researchers should be able to observe evidence of neural entrainment using an objective measurement tool that can discern changes in brain waves, such as an electroencephalogram (EEG).

One review article showed increased phase synchronization in lateral temporal areas of the brain with 5 Hz binaural beat stimulation (Chaieb et al., 2015). They found that 5 Hz for 15 min, two times a day, for 15 days resulted in a greater increase in verbal recall ability, whereas a single 30 minute 7 Hz session actually decreased verbal recall. This could be because an increase in binaural beat listening duration could lead to mental fatigue, or perhaps that some individuals may need shorter, successive sessions to see improvements in working memory. Scientists speculate that the more an individual’s brainwaves synchronize, the greater the positive effects of on cognition and concentration. There’s empirical support for the idea that greater synchrony in activity across the brain is associated with better cognitive performance (Hummel & Gerloff, 2005). However, others are less convinced and consider evidence of brainwave entrainment to be nothing more than artifacts that are inconclusive of any substantial cognitive improvements.

Scientists speculate that the more an individual’s brainwaves synchronize, the greater the positive effects on cognition and concentration.

Can binaural beats affect behavior?

In one study that sought to determine whether binaural beats improve attention for rapidly occurring visual stimuli, researchers found that, although performance did not increase during a single session, after a night of sleep consolidation performance was highest after simulation with a perceived 40 Hz binaural beat (Ross & Lopez, 2020). Another study demonstrated better cognitive flexibility when participants were given a dual task paradigm to measure their reaction times. (Hommel et al., 2016). To date, there remains a lot of variability in the reported effects of binaural beats on attention and concentration, so more research is needed.

A 2017 review of 33 randomized controlled trials showed that, for a working memory task, the application of 40 Hz for 20 min improved performance in healthy young adults (Kanzler et al., 2021). Research conducted by the University of Bristol showed that binaural beats may cause altered neural connectivity that promotes increases in cognitive performance and memory (Abaid et al, 2016). Researchers used five different acoustic stimulation conditions: pure tone, classical, 5 Hz, 10 Hz, and 15 Hz for participants during a working memory assessment and measured EEG changes. The binaural beats increased accuracy during the working memory task; they also observed measurable changes in EEG amplitude, showing that the connections between the frontoparietal and parietal-occipital cortices can be increased as a result of exposure to binaural beats (Abaid et al, 2017). This increase in connectivity is likely responsible for quicker neural processing. Contrarily, several prominent studies contradict these findings by reporting no enhancement of the EEG spectral power when exposed to theta, beta, gamma, or alpha frequencies, although the researchers did point out this may be due to a smaller sample size (Caballero & Escera, 2017). Another study showed the greatest differences in the temporal and parietal regions of the brain using beta binaural beats. However, desynchronization was also seen when the participants were exposed to theta binaural beats meaning that the participants were actually disturbed listening to the theta beats.

So: What do we know?

It appears possible for binaural beats to modulate our behavior and cognition through subjective experience. However, conclusive, replicable evidence remains elusive. Some of the existing studies are contradictory and unclear. Regardless, the progress made over the last five years is definitely noteworthy. It would be helpful for future studies to recruit larger sample sizes and to employ double-blind randomized control paradigms. For a potential future direction, neuroscientists should investigate how long the effect of binaural beats lasts as well as other possible clinical applications.

It appears possible for binaural beats to modulate our behavior and cognition through subjective experience. However, conclusive, replicable evidence remains elusive.

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Written by Jasreen Singh
Illustrated by Federica Raguseo
Edited by Chris Gabriel, Zoe Guttman, and Lauren Wagner

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References
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