Proponents say that listening to BBT can have benefits for both body and mind, including improved mood, better will-power, enhanced memory, less anxiety, increased pain control, lower blood pressure and better sleep. But what exactly is BBT, and can it really enhance our lives?
Getting the beat
Binaural beats are a perceptual phenomenon that occurs when two tones of slightly different frequencies are presented to the left and right ears, respectively. The listener perceives them as a single tone that varies in amplitude at a frequency equal to the frequency difference between the two tones. So, combining tones of 100 and 110 Hz produces a third tone with a perceived frequency of 105 Hz that rises and falls in amplitude with a frequency of 10 Hz. The third tone is not an actual sound, but an electrical stimulus that can only be perceived within the brain as a result of the two brain hemispheres responding simultaneously to each separate sound. This perceived stimulus is known as a 'binaural auditory beat'.
Binaural beats were first discovered by German experimenter Heinrich Wilhelm Dove more than 150 years ago, but only recently has the phenomenon been harnessed to produce desirable effects in the brain. It's believed that when binaural beats are played continually in the ears, brainwaves are entrained to speed up or slow down, depending on their frequency. This 'frequency-following response' is said to elicit changes in the listener's state of consciousness that can bring about a variety of benefits. 'Hearing' binaural auditory beats in the delta (1-4 Hz) and theta (4-8 Hz) frequency ranges, for example, is reportedly associated with enhanced creativity and improved sleep, while binaural beats in the beta (16-24 Hz) frequency range are said to boost attention and memory.
There's now an entire industry built on the idea that listening to binaural beats can improve health and contribute to personal development, with many companies offering a range of CDs and MP3 downloads, each claiming different benefits. Although many of the claims are controversial and have yet to be proven, in fact, there's a decent amount of research on BBT-and some promising findings.
A US study published in the peer-reviewed journal Physiology & Behavior looked at the effects of binaural beats on the performance of an alertness task as well
as on mood in 29 volunteers. Each volunteer performed the task on three different days while listening to a tape of either background noise containing binaural beats (in the beta range or the theta/delta frequency ranges), or background noise without binaural beats. All recordings sounded identical and participants weren't told about the presence of binaural beats.
The results showed that the beta binaural beats were associated with better performance in the altertness task and less negative mood, compared with the other conditions. "This technology may have applications for the control of attention and arousal and the enhance-ment of human performance," the researchers said (Physiol Behav, 1998; 63: 249-52).
More recently, a UK study found that listening to binaural beats may reduce preoperative anxiety. In the randomized controlled trial, patients undergoing general anaesthesia for day surgery listened to a soundtrack embedded with binaural beats or an identical soundtrack without binaural beats, or had no intervention. The researchers found that anxiety scores decreased significantly more with binaural beats compared with the other two groups: 26.3 per cent vs 11.1 per cent and 3.8 per cent, respectively (Anaesthesia, 2005; 60: 874-7).
Binaural beats might also benefit patients with more generalized anxiety, according to a Canadian study. In patients with mild anxiety, listening to binaural beat tapes in the delta/theta range resulted in lower anxiety scores reported daily in their diaries. However, the trial was uncontrolled and only involved 15 patients (Altern Ther Health Med, 2001; 7: 58-63).
Another small pilot study suggested that binaural beats may help children with attention-deficit/hyperactivity disorder (ADHD). Twenty participants were randomly assigned to listen to either an audio programme containing binaural auditory beats or a sham audio pro-gramme with no binaural beats for 20 minutes, three times a week for three weeks. Various tests were used, including the 'Homework Problem Checklist', to assess attention before and after the trial.
The results revealed that listening to binaural beats did not significantly reduce the symptom of inattention. However, both the children and their parents stated that homework problems due to inattention improved during the three-week study. They also reported that the programme was easy to use and helpful. The researchers concluded that binaural beat technology should be studied over a longer period of time in a larger sample population to further assess its effectiveness in reducing the inattention symptom in those diagnosed with ADHD (J Pediatr Nurs, 2010; 25: 3-11).
Other studies of binaural beats, however, have been less positive. One trial published in the Journal of Alternative and Complementary Medicine found that listening to binaural beats with an overlay of 'pink noise' resembling the sound of rain had no effect on brainwave activity compared with listening to the overlay without the binaural beats. In fact, the data indicated an increase in depression and a decrease in immediate verbal memory recall following the binaural-beat listening session compared with the control session. However, this study involved only four adults, each of whom served as his/her own control (J Altern Complement Med, 2007; 13: 199-206).
Another controlled trial reported that listening to binaural beats for seven minutes had no effect on blood pressure or heart rate in a small group of older adults. But the study author noted that this may have been because the sounds were not played long enough for the brain to either perceive and/or resonate to the binaural frequency. Another possible explanation is that "older brains may not perceive the binaural beats as well as younger brains", he said (J Hosp Mark Public Relations, 2008; 18: 213-9).
The Hemi-Sync system
One of the most studied forms of BBT is a system called Hemi-Sync, short for 'hemispheric synchronization', developed by American researcher Robert Monroe. Through the auspices of The Monroe Institute (TMI), a non-profit educational and research organization, Hemi-Sync has been refined with some 50 years of research and development, and continues to be the focus of a variety of specialized research projects by notable medical institutions and universities.
The findings suggest that Hemi-Sync can indeed alter brainwave activity and may have range of practical applica-tions-from improving memory to helping children with attention- and learning-deficit disorders. However, much of the research has been published by TMI's own in-house journal rather than by independent, peer-reviewed publications (see www.monroeinstitute.org/journal/).
Nevertheless, a number of studies published in the journal Anesthesia & Analgesia have shown that listening to Hemi-Sync recordings during surgery can reduce analgesic (painkilling-drug) requirements. One recent randomized controlled trial reported that the use of Hemi-Sync sounds before and during general anaesthesia "reduces intra-operative analgesic requirements, postoperative pain scores, and discharge time" (Anesth Analg, 2010; 110: 208-10).
An upbeat future?
So far, the scientific research into BBT has given us promising evidence that binaural beats may have positive effects on the brain, although the findings are far from conclusive. Indeed, as usual for a novel technology, larger and longer-duration studies are still needed, as most of the claims have been based on only small, preliminary, pilot studies and, so, have yet to be confirmed as applying to either a specific or general population.
WDDTY VOL. 22 NO. 5