Optical illusions mess with how we see things. “Binaural beats,” a type of auditory illusion, mess with how we hear things—and may play tricks in other ways, too.
Photo credit: Darekm135 / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)
An odd thing happens when you listen through headphones to two steady tones at slightly different frequencies, one in each ear. You start to hear a low beat that sounds like it’s coming from inside your head. But this third sound is just a figment of your brain’s auditory system. A phantom pulse.
What’s up with that? Scientists have known for decades that our brainwaves tend to synchronize, or “entrain,” with the rhythms we hear. In theory, slightly mismatched tones may confuse the brain. If one ear picks up a tone at 550 Hertz, while the other hears 558 Hertz, the brain will perceive a third frequency—binaural beats—at the points where the sine waves bump together.
Researchers haven’t fully studied binaural beats, let alone the possible health effects. But that hasn’t stopped an overkill of apps from marketing them as “digital drugs” with the power to relieve migraines, sharpen mental focus and blast away stress.
Even Bayer, maker of Aspirin, promotes binaural beats as “good vibes” for relaxation on its Austrian website.
So far, however, the evidence of any health benefits is thin.
So far, the evidence of any health benefits from binaural beats is thin
The latest study to poke holes in the hype comes from an international team led by scientists at the Montreal-based Laboratory for Brain, Music and Sound Research.
In the study, published this week in eNeuro, healthy adults wore head caps with electrodes for monitoring brainwaves using electroencephalography (EEG).
First, they listened to a series of binaural beat frequencies. Next, the same volunteers listened to frequencies mixed on a computer to create a third beat before the sound reached the ears. In this case, the third beat was part of the audio mix (and not an illusion).
After each session, the listeners rated their levels of mental relaxation, alertness and feelings of absorption in the experience.
The researchers found that binaural beats did entrain the brain—but not as much as the premixed beats. What’s more, neither had any effect on mood. A previous study, published in 2017, reached similar conclusions.
This didn’t surprise me. The mood-boosting effects of music, based on a large body of research, stem from the brain’s pleasure and reward response to our favorite sounds. Binaural beat apps use computer-generated frequencies, many of which sound only vaguely like music.
The Montreal study, to be fair, involved just 16 participants and listening sessions of eight minutes each. Chances are this study won’t put the nail in the coffin for binaural-beat diehards.
Whether binaural beats can cause a “high” remains debatable, but the power of suggestion can be intense
Digital drugs have a cult following online. Teens have posted YouTube videos of themselves “getting high” on audio tracks. Reviewers on iDoser’s website have raved about the trippy experiences they’ve had. Whether binaural beats can cause a “high” remains debatable, but the power of suggestion can be intense.
And some studies have shown possible benefits. A 2018 analysis of 22 studies concluded that binaural beats may help lower anxiety and offer modest pain relief.
Behavioral studies, however, tend to search for specific effects, such as relaxation. This approach can bias the results, noted Joydeep Bhattacharya, a cognitive psychologist who has studied the neuroscience of music. Binaural beats, he said, in an interview with Discover magazine, “raise a lot of flags.”
The few studies that have used brain imaging to understand what’s happening during binaural beats have produced inconclusive results, he pointed out. “That gives you a good indication that the story is more complicated than many of the behavioral studies want to convince you.”
Until more research is done, our best bet might be to see this phenomenon as a quirk of our gray matter—a bit of mischief from the proverbial ghost in the machine.
Disclaimer: Discussions about health topics provided in this blog, or in any linked materials, are not intended and should not be construed as medical advice, nor is the information a substitute for professional medical expertise or treatment. The author accepts no responsibility or liability for any health consequences relating to information published on this blog.