Today we're going to put on our headphones, kick back in the beanbag, and get mellow to the soothing sounds of the latest digital drug: binaural beats. These computer generated sound files are said to massage your brain and produce all sorts of effects, everything from psychedelic experiences to behavior modification. Let's point our skeptical eye at the science of binaural beats, and especially at some of the claims made for them.
First of all, I'm sure you're curious right off the bat to hear what binaural beats sound like, so let's take a listen:
A binaureal beat is created by playing a different tone in each ear, and the interference pattern between the slightly differing frequencies creates the illusion of a beat. It's intended to be heard through headphones, so there's no cross-channel bleed across both ears. Listen to this, I'll play a simple binaural beat, and I'll slide the pan control back and forth from one ear to the other. You can see that there isn't actually any beat, it's just an acoustic illusion:
If you search the Internet for "binaural beats" you'll quickly find there's a whole industry built on the idea that listening to binaural beats can produce all kinds of desired effects in your brain. It can alter your mood, help you follow a diet or stop smoking, get you pumped up for a competition, calm you down, put you to sleep, enhance your memory, act as an aphrodisiac, cure headaches, and even balance your chakra. Binaural-Beats.com offers a $30 CD that they call the world's first "digital drug". They claim it can get you drunk without the side effects. I-Doser.com offers a range of music tracks that they say simulates a variety of actual pharmaceuticals, such as Demerol, Oxycontin, and Vicodin. Suffice it to say that no matter what superpower you're looking for, someone on the Internet sells a binaural beat audio file claimed to provide it.
You don't have to buy one, though. It's not too hard to make your own binaural beat, and free software is widely available to do just that. The one that I used to make that little sample is an open-source program called Gnaural, available on the Sourceforge web site. It's pretty easy to use, though it takes some practice before you can generate some of the really cool, more professional sounding beats. A binaural beat consists of two simple tones, and most people add that background pink noise. Nothing special.
But the question is: Does it have a special effect on the brain? A lot of people think so. The basic claim being made for binaural beats is "resonant entrainment". Entrainment, in physics, is when two systems which oscillate at different frequencies independently are brought together, they synchronize with one another, at whatever the combined system's resonant frequency is. Examples of entrainment occur in animals in nature; for example the chirping of crickets or the croaking of frogs. Synchronization of menstrual cycles in women is another example. Even people coming together and dancing with one another is a type of entrainment. The basic claim for binaural beats is that the perceived low-frequency beat will entrain your brain wave pattern, thus forcing your brain into some desired state.
Most of these web sites give some brief explanation of entrainment. The example you hear most often is that of Dutch polymath Christiaan Huygens, who in 1665, hung two pendulum clocks next to each other on a wall. He noticed that the pendulums eventually matched each others' frequency, but always in antiphase, opposite to each other, as if canceling each other out. He'd try disturbing one or setting them in sync, but they'd always return to the same antiphase synchronization. Huygen's experience is widely touted on binaural beat websites as a demonstration of how systems can become spiritually connected through some energy field. However, they misunderstand what happened, and have not read the full story. Huygens also tried taking one clock off the wall, and as soon as they were no longer physically connected to one another via the actual wall, the effect disappeared. It was not the proximity of the clocks to one another that created the entrainment; it was their physical, mechanical connection to one another. As each pendulum swung it imparted an infinitesimal equal and opposite reaction to the wall itself. With two clocks on the wall, the system naturally sought the lowest energy level, according to the laws of thermodynamics; and both pendulums would thus swing exactly counter to each other, minimizing the system's total energy.
So to summarize their claim, they're saying that entrainment means that a binaural beat will cause your brain's electroencephalogram to match the pattern of the phantom beat. Well, if it did, entrainment certainly doesn't apply and would not be part of the equation, so we can scratch that off the list. But it doesn't make the claimed observation wrong. We do know that certain electroencephalogram waveforms are often associated with certain kinds of activity. For example, physical activity or REM sleep often produces an electroencephalogram with a sine wave of between 4 and 8 Hz, which we term a theta pattern. Waking relaxation with eyes closed often produces a pattern from 8 to 12 Hz, which is called an alpha pattern. There are only a few characterized patterns, and pretty general descriptions of what kinds of activities go with them. The claim made by the binaural beat sellers depends on much more granular and specific matches. For example, the claim that a binaural beat with a frequency of X produces the same effect in your brain as Vicodin is wholly implausible. Such claims presume that we know the exact frequency of the electroencephalogram in each of these desired conditions, and the fact is that brain waves don't work that way. It is wholly and absolutely implausible to say that desired brain condition X will occur if we get your EEG to read exactly X Hz.
Not only that, binaural beats presume that brain waves work in the opposite way that they do. Certain brain states produce certain brain waves; brain waves don't produce brain states. You just don't turn a dial to 6.5 Hz and induce instant happiness.
And so, while the claimed science behind binaural beats is unfounded, this doesn't mean that the effect isn't real and simply unexplained. Maybe you can listen to a certain binaural beat and induce a desired state, but for reasons we don't yet understand. So let's take a look at the research, and see if such an effect has actually been observed.
A 2008 study at Hofstra University played two different binaural beats and a control sound (a babbling brook) to patients with high blood pressure. There was no difference between the groups. In one small study from Japan that was published in the Journal of Neurophysiology in 2006, they played various binaural beats to nine subjects, and observed the resulting EEGs. They found great variability in the results. Their conclusion was that listening to binaural beats can produce activity on the human cerebral cortex, however the cause was more likely a conscious auditory reaction and was not correlated to the frequency of the binaural beat. However, a 2005 study published in Clinical Neurophysiology found that they were able to induce a desired frequency in the EEG matching the phantom beat frequency encoded in a binaural beat, however this was with a single subject and was neither blinded nor controlled.
But we don't need any studies to tell us that different people can listen to different kinds of music and be affected. A lot of people who work out have a workout playlist on their iPod that keeps them energized. Some people listen to certain music to help them fall asleep. The Muzak company has built an industry on relaxing music that will keep people in the mood to shop. Music does affect our mood, and so we already have every reason to expect binaural beat recordings to produce the same effect. Different people may find certain binaural beats to be relaxing or energizing. But, we've never found any reliable indication that a binaural beat's connection to our brain is any deeper or more meaningful than any other music track. We do know for a reasonable certainty that specific claims made by most sellers of binaural beats are not credible, and that there is no reason to think that the effect they're claimed to produce will work for you.
Well, except for one reason: The power of suggestion. If I give you a music track and tell you that it will cure your headache, you're more likely to report that it cured your headache than you are to say "Well it didn't effect my headache, but it made my short-term memory better." An interesting experiment would be to buy a binaural track claimed to induce drunkenness, for example; play it for five friends without telling them the claim, and then ask how it made each of them feel. Give them multiple choices to select from. Chances are they're going to respond all over the map. If you have a friend who is a believer in binaural beats, I suggest going ahead and setting up this little test.
So, in summary, binaural beats certainly do not work the way the sellers claim, but there's no reason to think they're any less effective than any other music track you might listen to that effects you in a way you like. If they make you sleepy (like they all do for me), use them to go to sleep. If they relax you or get you amped, use them for that. But don't expect them to be any more effective than regular music. If someone you know claims that they are, put them to the test, and bust the myth.
Cite this article:
Dunning, B. "Binaural Beats: Digital Drugs." Skeptoid Podcast. Skeptoid Media,
31 Mar 2009. Web.
14 Feb 2016. <http://skeptoid.com/episodes/4147>
References & Further Reading
Adams, C. "Can Binaural Beats Improve Your Mood?" The Straight Dope. Creative Loafing Media, Inc., 30 Jul. 2010. Web. 13 Feb. 2012. <http://www.straightdope.com/columns/read/2949/can-binaural-beats-improve-your-mood>
Carter, C. "Healthcare performance and the effects of the binaural beats on human blood pressure and heart rate." Journal of Hospital Marketing and Public Relations. 1 Aug. 2008, Volume 18, Number 2: 213-219.
Karino, S., Yumoto, M., Itoh, K., Uno, A., Yamakawa, K., Sekimoto, S., Kaga, K. "Neuromagnetic responses to binaural beat in human cerebral cortex." Journal of Neurophysiology. 21 Jun. 2006, Volume 96, Number 4: 1927-38.
Padmanabhan, R., Hildreth, A.J., Laws, D. "A prospective, randomised, controlled study examining binaural beat audio and pre-operative anxiety in patients undergoing general anaesthesia for day case surgery." Anaesthesia. 7 Jul. 2005, Volume 60, Number 9: 874-877.
Pratt H., Starr A., Michalewski H.J., Dimitrijevic A., Bleich N., Mittelman N. "Cortical evoked potentials to an auditory illusion: Binaural beats." Clinical Neurophysiology. 1 Aug. 2009, 120, 8: 1514-1524.
Schwarz, D.W., Taylor, P. "Human auditory steady state responses to binaural and monaural beats." Clinical Neurophysiology. 1 Mar. 2005, Volume 113, Number 3: 658-668.