Illustration: Matija Medved


How to Hack Your Brain with Sound

Binaural beats may be able to entrain your brainwaves. That sounds more magical than it is.

Optimize Me is an Elemental column exploring (and fact-checking) the weirdest self-improvement trends. It comes out every Tuesday.

WWhat if I told you there was something that could improve your focus and attention, alleviate pain and anxiety, and help you meditate and sleep better at night? And, best of all, it’s free, with virtually no side effects. Sounds too good to be true, but that’s the reputation of binaural beats, a seemingly magical tone that has been imbued with all of these benefits.

Binaural beats are actually an auditory illusion that occurs when you play two tones of similar but not identical frequencies, one in each ear (binaural means relating to both ears). The brain wants to reconcile the two sounds, so what you end up perceiving is actually a third tone that’s the difference between the two, an illusion produced in the brainstem. For example, if a 400 hertz (Hz) tone and a 410 Hz tone were played into your left and right ears, respectively, you would perceive a 10 Hz rhythmic pulse — the binaural beat. (To hear what binaural beats sound like, click here.)

Here’s where the seemingly magical part comes in: Activity in the brain starts to match the frequency of the binaural beat. In the example above, the brain would begin firing at 10 Hz. This process is called brainwave entrainment, and it’s one way people are trying to hack their brain state to achieve a desired mental state.

“The attractiveness of binaural beats (in theory) is that this tiny difference between the two tones is going to entrain our brains to work at a desired frequency,” says Miguel Garcia-Argibay, a scientist at Örebro University in Sweden who researches binaural beats.

The goal is that by getting your brain to fire at the desired rate, you’ll begin to embody the corresponding mental state.

The brain runs on electricity, and neurons fire at different rates and patterns depending on what they’re doing. Specific brainwave frequencies, typically measured from the scalp using electroencephalography (EEG), are associated with different cognitive and emotional states.

  • Gamma waves are the highest frequency at 30 hertz (Hz) and up, meaning neurons are firing at the rapid pace of 30 times or more every second. This brain state is associated with intense concentration.
  • Beta waves run at 12 Hz to 30 Hz and are tied to feelings of arousal, attention, and anxiety.
  • Alpha waves slow down to 8 Hz to 12 Hz and are related to a more relaxed and passively attentive state, as well as feeling drowsy.
  • Theta waves at 4 Hz to 8 Hz signify deep relaxation and an inward focus and are often detected during meditation.
  • Delta waves are the slowest, firing just 0.5 to 4 times per second. If you’re in delta waves, you’re probably asleep.

With entrainment, brainwaves start to match the frequency of an external stimulus, like a binaural beat, and brain areas that might ordinarily fire at different rhythms become synchronized. The goal is that by getting your brain to fire at the desired rate, you’ll begin to embody the corresponding mental state. For example, if you need to study for a test or focus at work, nudging your brain activity into gamma or beta waves could enhance your attention. At the other end of the spectrum, people with insomnia might try to trick their brain into slowing down to a theta or delta frequency to help them fall asleep.

While it sounds great in theory, just how effective binaural beats are at entraining the brain, and whether entrainment actually makes a difference in mood or cognition, is still up for debate.

Hector Orozco Perez, a machine learning developer who researched binaural beats as a student at McGill University in Canada, says that while binaural beats are “sold as a cognitive enhancer,” the research backing up the claims “were very wishy-washy. It was very unclear if binaural beats actually had any effect at all.”

Studies investigating the effects of binaural beats have been conflicting. In a recent meta-analysis comparing 22 studies on the phenomenon, Garcia-Argibay found that theta frequencies really can reduce people’s anxiety levels, and gamma frequencies improved performance on attention tasks. The effect of binaural beats on memory was less concrete, though. Some studies showed better performance on memory tasks after people were exposed to beta, alpha, and theta frequencies, but others reported worse performance after each of these binaural beat frequencies.

It’s also not entirely clear that binaural beats can even cause brainwave entrainment. In one particularly damning study, binaural beats presented at each of the five brainwave frequency categories had no effect on EEG recordings. However, other research did see changes in EEG activity measured inside the skull in patients who were undergoing brain surgery in response to four different beat frequencies. Another study showed entrainment to theta waves in several areas of the brain after 10 minutes of theta binaural beat exposure.

Garcia-Argibay says one reason for these discrepancies is because there is no agreed-upon protocol for studying binaural beats, and each of the experiments used different methods — what frequency the beats are presented at, how loud, how long, whether music is playing over-top, and whether the sound is presented before a person performs a task or during. What seemed to work the best, according to the meta-analysis, is playing the tones on their own (no background music or white noise), for at least 10 minutes, before the target task.

An interesting twist in the binaural beat story is that they might not be the only auditory stimulus that can cause brainwave entrainment. A recent study by Perez published last month in the journal eNeuro showed that while binaural beats did cause brainwave entrainment, so did monaural beats — a pulsing sound presented at the same frequency in each ear. In fact, entrainment was stronger with the monaural beats, but neither sound had any impact on people’s mood or state of mind.

Perez says there’s likely nothing unique about binaural beats’ effect on the brain. In fact, in the field of auditory cognitive neuroscience, scientists have long known that even a simple rhythmic sound, such as clapping, will entrain the brain. “Any kind of rhythmic sound will entrain your brain to the frequency of the rhythm,” he says, “so why are people losing their minds over something so simple?”

Health and science writer • PhD in 🧠 • Words in Scientific American, STAT, The Atlantic, The Guardian • Award-winning Covid-19 coverage for Elemental

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