Binaural beats (BB henceforth) stimulation is a non-invasive brain entrainment that is conducted by presenting different frequencies of sound to each ear (Oster, 1973). It is based on findings from auditory system research, showing that in such a case, the brain produces a third “phantom” sound which is a frequency that is the difference between the two tones presented to the ears (Bori-syuk, 2002, Fitzpatrick, 2009, Cotillon, 2000, Scott, 2009). Listening to such manipulated frequencies affects neural networks and functions in a way that results in improving cognitive performance (Beauchene, 2016).
THE FREQUENCIES OF THE BRAIN
With some exercises presented to the brain, Binaural beats are used as part of the auditory input to the trainee. They differ in frequencies and target based on what the brain is about to train. The range of frequencies used is:
• Delta pattern: Binaural beats in the delta pattern operate at a frequency of 0.5–4 Hz with links to a dreamless sleep. People who received a delta pattern frequency during sleep entered a deeper stage of sleep, according to electroencephalogram (EEG) brain scan results.
• Theta pattern: Practitioners set binaural beats in the theta pattern to a frequency of 4–7 Hz. Theta patterns contribute to improved meditation, creativity, and sleep in the rapid eye movement (REM) phase.
• Alpha pattern: Binaural beats in the alpha pattern are at a frequency of 7–13 Hz and may encourage relaxation.
• Beta pattern: Binaural beats in the beta pattern are at a frequency of 13–30 Hz. This frequency range may help promote concentration and alertness. However, it can also in-crease anxiety at the higher end of the range.
• Gamma pattern: This frequency pattern accounts for a range of 30–50 Hz. study suggest that these frequencies promote maintenance of arousal while a person is awake.
BINAURAL BEATS AND COGNITIVE PERFORMANCE
Different BB frequencies have been shown to effect areas in the frontal and parietal cortex (Draganova, 2008, Pastor, 2002, Ross, 2014, Schwarz, 2005). BB frequencies are produced to match the neural oscillations in the brain, covering the five brainwaves: delta;1-4Hz (Walker et al., 1999); Theta;4-8Hz (Lega, 2012); Alpha;8-12Hz (Foster, 2017); Beta;13-30Hz (Rangaswamy, 2002) and Gamma;30-150Hz (McDermott, 2018). Relating to working memory functions, stimulating the beta (13-30Hz) and gamma (above 30Hz) frequencies increased the coherence between frontal and parietal neural networks (Lutzenberger, 2002, Babiloni, 2004).
For example, when performing an N-Back task, which is a working memory task in which partici-pants are required to respond if a stimulus seen on a screen was already presented to them n trials before (Owen et, al., 2005), it has been shown that listening to 15Hz (Beta) improved accuracy as well as strengthened the connection within the cortical networks involved (Beauchene et al. 2016). A specific brain area involved in attention that its function has been suggested to be affected by BB is the reticular formation (Wahbeh, 2007). Some studies suggest that BBT has an impact on the structure of cortical connectivity networks, which in turn effects the network topol-ogy of improved memory functions (Ioannou, 2015). This was specifically shown using alpha band (8-12hz) beats, which was the band used in our study.
The Alpha frequency and attention, working memory, perceptual abilities and information processing speed
Indeed, the positive effect of alpha-range BB (8-12Hz) on cognitive functions, has been specifically associated with attention, working memory, perceptual abilities and information processing speed (Braboszcz,2011; Clark, 2004; Freunberger, 2011; Lachat, 2012; Oprisan, 2004; Palva, 2007; VanRullen, 2003). For instance, higher amplitude of alpha oscillations was positively correlat-ed with improved capacity of working memory (Sauseng, 2009). Better performance in the Stroop Effect task was shown to be associated with alpha wave synchronization induced by BB, indicating improvement in divergent thinking and in cognitive processing (Fink et al., 2006, 2009 and Cruceanu & Rotarescu, 2013 respectively). In healthy older adults (65+), two-min exposure to alpha BB resulted in improvement in forward and backward Digit Span Memory Tasks (McMurray, 2006).
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