Previous studies investigating steady-state responses and the topographical distribution of cortical responses to monaural and binaural beats have reported maxima at frontocentral, mid-sagittal and temporal regions for both monaural and binaural beat stimuli ( Karino et al., 2006 Draganova et al., 2008 Pratt et al., 2009). The binaural beat sensation is often described as being subjectively located “inside” the head and is understood to be modulated at the level of the brainstem in the superior olivary nuclei, whereas monaural stimuli are modulated at the level of the cochlea ( Regan and Regan, 1988 Draganova et al., 2008). For example, presentation of 40 Hz oscillations to the left ear and 45 Hz oscillations to the right ear results in the perception of an amplitude-modulated (“beat”) stimulus of 5 Hz. In contrast, binaural beats occur when sine waves with neighboring frequencies are presented to each ear separately. As both ears receive the same beat wave, perception of the beat does not require an integration of information from the two ears ( Pratt et al., 2009).

This physical beat signal is modulated first in the cochlea and then relayed via brain stem neurons to the auditory cortex (Figure 1). Monaural beat stimulation is achieved by applying the same amplitude-modulated signal to both ears simultaneously. However, the majority of studies looking at the effects of auditory beats have been performed using binaural beat stimuli despite evidence suggesting that cortical responses to monaural beat stimuli are stronger than those to binaural beats ( Schwarz and Taylor, 2005 Draganova et al., 2008).Īuditory beats are amplitude-modulated signals, which can be generated by the superposition of two auditory sine waves with neighboring frequencies, in one of two ways. The application of auditory beats either monaurally (i.e., physical beats delivered to both ears) or binaurally (two different sine waves of neighboring frequencies delivered to each ear separately), may also be a promising new tool with which to target cognition in a reversible, non-invasive way. Our results indicate a role for monaural beat stimulation in modulating state anxiety and are in line with previous studies reporting anxiety-reducing effects of auditory beat stimulation.Įmerging studies have shown that auditory beat stimulation can affect mood states in terms of levels of anxiety ( Le Scouarnec et al., 2001 Padmanabhan et al., 2005 Weiland et al., 2011) and well-being ( Lane et al., 1998 Le Scouarnec et al., 2001 Wahbeh et al., 2007a). When evaluating responses for the individual beat frequencies, positive effects on state anxiety were observed for all monaural beat conditions compared to control stimulation. Monaural beat stimulation was found to reduce state anxiety. After each stimulation period, participants were asked to evaluate their current mood state and to perform cognitive tasks examining long-term and working memory processes, in addition to a vigilance task. Theta (6 Hz), alpha (10 Hz) and gamma (40 Hz) beat frequencies, as well as a control stimulus were applied to healthy participants for 5 min. We aimed to target states related to anxiety levels and general well-being, in addition to long-term and working memory processes, using monaural beats within the range of main cortical rhythms. Therefore, we examined the impact of monaural beat stimulation on anxiety, mood and memory performance. In spite of reportedly similar EEG effects of binaural and monaural beats, data on behavioral effects of monaural beats are still lacking.

2Department of Neuropsychology, Faculty of Psychology, Institute of Cognitive Neuroscience, University of Bochum, Bochum, GermanyĪpplication of auditory beat stimulation has been speculated to provide a promising new tool with which to alleviate symptoms of anxiety and to enhance cognition.

1Department of Epileptology, University of Bonn, Bonn, Germany.

Wilpert 1, Christian Hoppe 1, Nikolai Axmacher 2 and Juergen Fell 1

Impact of filebeats