Effect of Binaural Stimulation on Attention and EEG

Background

The focus of this study was on identifying the effects of binaural beat (BB) stimulation on participants’ cognitive abilities and electroencephalogram (EEG) brainwave activity. Anecdotal reports in the existing field of literature on BB’s ability to increase EEG activity and arousal levels were the motivators for this study and the topics the authors wanted to test. The authors cited multiple sources of previously conducted BB experiments and criticized their lack of a rigidly organized double blind study to ensure the validity of their findings. Many self-reported cases were identified where participants expressed their opinions that they felt more alert or were able to concentrate better after exposure to various BBs. However these opinions could be susceptible to the placebo effect of participants knowing they are being exposed to BBs. Additionally, marketing companies spread the idea that BB producing products are effective at increasing concentration and are capable of helping users fall asleep faster and more restfully without showing evidence to prove such claims. This prior programming may have also influenced the participants in previous studies skewing their results.

Methods

This experiment consisted of a double blind study that was split into two groups. Group A consisted of 60 volunteers (28 females, 32 males) from Madrid with an average age of 28.9 and a standard deviation of 4.3 years who were to be evaluated on their cognitive abilities following 20 minutes of BB exposure. The groups were randomly split into three subsections of 20 each who would experience different sounds: 1) Commercially available binaural audio beat within a pink noise background; 2) a placebo group with just a pink noise background; 3) and a self-made collection of four BBs overlapping at once within a pink noise background.  The exclusion criteria for involvement in this group was that participants had to have no neurological diseases and could not be left-handed. Each participant also had to pass a hearing test. The participants were instructed to sit comfortably in a room with their eyes closed and listen to the audio for 20 minutes before conducting a series of three tests designed to test their perception, process speed, and attention control.

Group B consisted of 18 volunteers (5 females, 13 males) from Madrid with an average age of 26.6 and a standard deviation of 7.5 years who were to have their brainwave activity monitored by an EEG following twenty minutes of exposure to BBs. This group was similarly divided into the three subcategories listed above, each with six participants. The exclusion criteria for this group was that participants had to have no neurological diseases and could not be right-handed. Each participant also had to pass a hearing test. The participants’ EEGs were monitored three minutes before the audio began to establish a baseline. Then they listened to the audio for 20 minutes in a comfortable position with their eyes closed as they were monitored by the EEG.

Findings

The results of the testing were that no scientifically significant improvements in cognitive abilities or EEG activity were recorded. In group A there were no significant differences within any of the three subgroups at either of the three tests. A non-parametric Kruskal-Wallis analysis of variance was performed. p < 0.05 was considered significant. See table two below.

In group B the EEG revealed no significant changes between the three subgroups. A non-parametric

Kruskal-Wallis analysis of variance was performed but could not find any significant differences between the three groups for any electrode, band, or moment of stimulation.

Criticism

The authors admitted that their sample sizes may have been too small to accurately generate enough data to substantiate findings. Additionally, they acknowledged that the exposure to BBs may have been too short to allow the participants time to acclimate. Finally, they speculated on the use of pink noise alongside the BBs within the experiment as a potential variable that could have disrupted the results. I agree that any of the three criticisms could have been a factor in the findings. I was also curious about the exclusionary criteria between the two groups. I’m unsure as to how being right or left handed impacts an EEG reading and why the authors decided to limit one group to left handers and one to right. Finally, I found the participant pool to be too varied for my taste. If I were to conduct a neurological experiment I would want my focus groups to be as similar as possible in age to limit the impact time has on brain function. The participants history of participation in contact sports along with medical records of any previous head trauma would also be valuable knowledge to possess. As would knowledge of the participants history with drugs and alcohol. 

This study is easily re-producible and with a few altercations as suggested above could prove to be a valuable addition to the field of study. As it is currently, I’m not sure the findings which suggest BBs do not improve concentration or alertness are backed by enough data to hold any significant weight in the current field of study. More research is necessary before binaural beats can be efficiently categorized in terms of their effectiveness.  

Source:

Crespo, A., Recuero, M., Galvez, G., & Begoña, A. (2013). Effect of binaural stimulation on attention and EEG. Archives of Acoustics, 38(4), 517-528.