There are reasons to assume that binaural beats might affect the size or scope of the attentional focus.

Even though some models suppose that global and local level information is selected from associated spatial frequency channels (Robertson & Lamb, 1991) or by binding level information to feature-like representations of the hierarchical structure (Hübner & Volberg, 2005 Volberg & Hübner, 2004), global precedence is generally assumed to indicate a bias towards a large, comprehensive attentional focus, while attending to local features is considered to require more attentional effort. Typically, this task gives rise to the “global precedence” effect (i.e., performance is better when responding to global than to local features), which implies that global features can be processed faster than local features. Participants are typically confronted with a global stimulus (e.g., large rectangle) that is made of smaller shapes (the local stimuli), and the relationship between global and local stimuli can be congruent (e.g., a large rectangle composed of small rectangles) or incongruent (a large rectangle made of small squares). This task assesses how fast people can process global versus local characteristics of hierarchically constructed visual stimuli (e.g., larger shapes made of smaller shapes). A well-known task that taps into this issue is the global–local task developed by Navon ( 1977). However, it is not yet clear how binaural beats affect attentional allocation over space. The size of the AB was considerably reduced by the binaural beats at least in some participants, which suggests that beats have a specific impact on how people allocate their attention over time. Participants listened to binaural beats while performing an attentional blink (AB) task, which assesses the efficiency of allocating attention over time. Very recently Reedijk, Bolders, Colzato, and Hommel ( 2015) have shown that binaural auditory beats affect how people control and monitor their visual attention. This suggests that high-frequency beats might facilitate attentional control, which would fit with the observation that high-frequency neurofeedback training over the frontal cortex improves attentional efficiency (Keizer, Verment, & Hommel, 2010). Low-frequency binaural beats are associated with mental relaxation and high frequency beats with alertness and attentional concentration (Vernon, 2009 Turow & Lane, 2011). These findings support the idea that the neural phase locking elicited by binaural beats can influence ongoing cognitive processing (Karino et al., 2006 see, Chaieb et al., 2015, for a recent review on the effect of binaural beats on cognition and mood).

While the neural mechanisms underlying this illusion are still unclear, very recent studies have shown that beat stimulation significantly affects functional brain connectivity (Gao et al., 2014) and modulates intracranial power and phase synchronization (Becher et al., 2015). When two beats of slightly different frequency (for instance 300 and 340 Hz) are presented separately to the left and right ears, the hearer detects a single beat that differs in amplitude at a frequency equal to the frequency difference between the two beats (40 Hz) a perceptual illusion known as the binaural auditory beat.

Binaural sounds