Headphones allow us to trick our brains into perceiving a sound that doesn’t actually exist.
Some people love headphones while they work at their computer. I’m not one of them. Some background music I can tolerate, but only when I know it so well it disappears into the background. In most cases, I find music and sounds distracting, especially when I need to concentrate. But external noises can distract too. For the past few weeks I’ve been working in a noisy environment, so I was experimenting with different white noise playlists that could give me some acoustic peace. I stumbled across binaural beats which are decidedly not new, but were new to me. Spotify has hundreds (possibly thousands) of tracks and playlists with binaural beats, many with claims to improve focus, offer stress relief, promote lucid dreams, and even boost your love life (who knew that 528 Hz was such an important frequency?). Some of the claims (actually, almost all of the claims) sounded too good to be true so I did a deeper dive – presented here for your reading and listening enjoyment.
What is a binaural beat?
When two different sound tones that are close, but not identical, in pitch are played together (one in each ear), your brain interprets a “beat”. Each ear must receive a dedicated tone for this to work – so you need headphones. Here is a sample:
If you listen with headphones, the sound should be gently pulsating. But remove one earphone, or the other, and the effect disappears. The beating you are perceiving is being entirely generated within your brain. it is an illusion. The beat that you perceive is the frequency difference between the two waves. For example, if one ear hears a 440Hz tone and the other hears a 480Hz tone, then the brain will perceive a 40Hz beat. This appears to originate in the auditory cortex and the brain stem. Binaural beats can be contrasted with monaural beat which are physically generated and objectively heard in either ear.
Binaural beats date back to the their discovery in 1839, and there has been considerable interest in them since, with the hypothesis that they could possibly induce effects in the brain. The idea, which has not been proven, is that the beats will nudge brain cells into firing at the same frequency, a term called “entrainment”. The intent is to use different frequencies of binaural beats with the goal of triggering the brain waves that naturally occur during different activities, ranging from delta waves (0.5-4 Hz, deep sleep) through theta (4-7 Hz, meditation, and REM sleep), alpha (7-13 Hz, relaxation), beta (13-30 Hz, concentration/alertness), and gamma (30-50Hz, arousal). Proponents claim that binaural beats can induce these brain waves, and consequently, these effects.
What does the evidence say?
The published evidence for binaural beats to affect brain activity or emotions seems positive, but not consistently so, with the strongest evidence looking less impressive. I could find no systematic reviews published in PubMed or cited elsewhere. PubMed has one meta-analysis published in 2018. Meta-analyses can be hit or miss, especially if the underlying trials themselves were poorly done. It included a total of 22 studies after applying search criteria. It concluded that there was robust evidence of a modest effect of binaural beats on memory, attention, anxiety, and analgesia. I also looked at some of the more widely cited papers. This 2017 study which was not included in the meta-analysis (it missed the search cutoff by a month) examined if binaural beats could affect EEG activity at the same frequency of the beat stimulation. It used a “placebo” which was an acoustically-generated beat. No effects on EEG activity were detected and no effects on heart rate or skin conductance (as a proxy for arousal) were found. The authors conclude that binaural beats are not an entrainment tool, nor do they have any clinically meaningful effects. Another study, this one with only 16 participants, was published in 2020 using similar controls and concluded that binaural beats could entrain the brain to some extent. However, monaural (control) beats entrained the brain more strongly than binaural beats. Neither form of beat had any effect on mood (it did not study memory or cognition). Is there something to the evidence? Possibly. Steven Novella looked at binaural beats in 2020 noting:
Applying my usual criteria to the claim that binaural beats improves memory, I would say the current research is suggestive but not definitive, genuinely warranting further research. Such claims become convincing when they not only replicate, but survive increasingly rigorous methodology, without suffering from the “decline effect” to either clinical or statistical insignificance. I also suspect that there may be a non-specific effect at work here, and at least this would need to be ruled out with careful controls. The question is, if there is a real memory-enhancing effect from specific frequencies of binaural beats, is that due to the increased cross-talk we are seeing in the brain, or is it rather due to a non-specific alerting effect from the stimuli itself? Might any stimulus that is sufficiently annoying or stimulating have the same effect?
This, in my opinion, is the critical question, assuming there is a real effect here at all. Are we really hacking the brain, or is this just a complicated way of producing a non-specific alerting effect?
Hype beyond the evidence
Pre-streaming-internet era, binaural beats were probably something that you purchased on CD or maybe even cassette. Now that streaming services and YouTube offer an unlimited array of binaural beats, the entry costs are low. There are some cool apps for you phone if you want to create your very own binaural beat, letting you choose the frequency of the beat and the base frequency. If you want “artisanal” beats, there’s a company that would very much like to sell them to you.
I’m listening to a “beta wave” binaural beat right now as I write this post, and while there is lots of chatter in my household. Is it helping me concentrate? Possibly, the drone synthesizer that overlays the beat drowns out most of the background sounds. And I personally find most of the audio tracks with binaural beats are easy enough to ignore after a while. Whether binaural beats do anything beyond a monuaral beat, or even white noise or music, remains an open question.