May 26, 2021 | Vanessa B. Sanchez, PennNeuroKnow
Have you ever put on music to help you study? Or to calm you down after a stressful day? Maybe you’re scrolling on Youtube right now trying to figure out what to listen to next…Well, have you ever considered listening to binaural beats?
What are binaural beats?
Binaural beats are a perceptual phenomenon (or illusion) that occurs when two different tones are presented separately to each ear1. When these two tones are presented, you, the listener, perceive the difference between the sound waves entering the left and right ear2-3.
For example, if the left ear registers a tone at 400 Hz and the right ear registers one at 410 Hz, what you actually hear is halfway between the two tones: 405 Hz – the binaural beat (Figure 1) 3,6. Because your brain is trying to interpret these two frequencies, this binaural beat of 405 Hz is considered an illusory tone3,6. Scientists from around the world have shown that in order for a binaural beat to occur, the difference between the two frequencies (e.g., 400 Hz – 410 Hz = 10 Hz) must be small (≤ 30 Hz)7. If the difference is not small ( 30 Hz), your ears will be able to capture the two tones separately and no binaural beat will be perceived6. Will you perceive a binaural beat if you listen to 10 Hz from both ears? No, because a binaural beat is the difference between the two frequencies, which is why it is considered an auditory phenomenon or illusory tone3,4,6!
How are binaural beats processed in the brain?
How your brain is processing these binaural beats is still not exactly clear. Some scientists believe the phenomenon of binaural beats is thought to occur through a process called interhemispheric coherence3,9. Your brain can be divided up into two major parts: the left and the right hemisphere. In each hemisphere lies a region called the auditory cortex, which is where and how auditory information (in this case binaural beats) gets processed. Normally, the sounds that your right and left auditory cortices are processing are very similar. When you listen to binaural beats, your auditory cortices become confused because they are trying to process the two different tones9. To solve this binaural puzzle, scientists believe that your auditory cortices communicate with each other more, and therefore become more synchronized9.
Some scientists believe that this synchrony is associated with your brainwaves1-10. Brain waves are electrical impulses that reflect how the neurons in your brain are communicating with each other10. These brain waves can occur at certain frequencies and can be either slow or fast. Your brain has five different types of brain waves that each fall within a certain range of frequencies. These types of brain waves represent what is called a brain state. For example, if your brain waves occur at high frequency (or what’s called the “gamma” or “beta” states), you are likely to be learning and deeply concentrated4,10. Other brain waves at a slower frequency like “delta” and/or “theta” states are associated with sleep and relaxation4,10. In between, are “alpha” states which are associated with reducing stress and positive thinking4,10. Interestingly, some scientists believe that the frequency of sounds that the auditory cortex is processing can affect the frequency of your brain waves4,6,8,10. So, if binaural beats are also in these lower frequencies like 4 – 8 Hz (theta state), it is thought that your brain waves will synchronize with these frequencies, which would then make you feel relaxed.
Is this true?
Dentists think so…
Many of us have experienced the anxiety that comes with getting our wisdom teeth removed. In one study, some patients were lucky enough to be offered a chance to listen to binaural beats before surgery. If they agreed, they listened to binaural beats (9.3 Hz ~ theta waves) through stereo headsets for 10 minutes and during this time they were given a local anesthetic7. Those who chose not to listen were just given the local anesthetic and sat alone, in silence, for 10 minutes. To measure anxiety levels scientists used a visual analog scale (VAS) before and after the 10 minutes (where patients either sat in silence or listened to binaural beats). You’ve probably seen a VAS at your local dentist’s office; it is just a line that represents a continuum of “no anxiety at all” to “worst anxiety imaginable” and can also be represented as 6 faces that go from a happy face (no anxiety) to a face with tears (worst anxiety)7. What scientists found was that those who chose not to listen to binaural beats leaned towards the right side of the spectrum: worst anxiety. Meanwhile, patients who originally reported high levels of anxiety and then listened to binaural beats (for 10 min) reported that their anxiety levels significantly decreased7. Remember, theta waves are associated with relaxation, so it is not surprisingly if these patients might have felt more relaxed after listening to binaural beats and reported lower anxiety levels. Overall, this interesting study suggests that listening to binaural beats can reduce anxiety levels in a variety of situations.
Other interesting studies that have been conducted on binaural beats show that they help to improve cognition, focus, motivation, memory, and even confidence!9 With all this in mind, I would encourage you to check them out – you never know unless you try. Curious? My favorite binaural beat to help me focus is here.
- Oster, G. (1973). Auditory beats in the brain. Scientific American, 229(4), 94-103.
- Lane, J. D., Kasian, S. J., Owens, J. E., & Marsh, G. R. (1998). Binaural auditory beats affect vigilance performance and mood. Physiology & behavior, 63(2), 249-252.
- Garcia-Argibay, M., Santed, M. A., & Reales, J. M. (2019). Efficacy of binaural auditory beats in cognition, anxiety, and pain perception: a meta-analysis. Psychological Research, 83(2), 357-372.
- Booth, S. (2019, May 14). This Is Your Brain on Binaural Beats. Retrieved March 25, 2021, from https://www.healthline.com/health-news/your-brain-on-binaural-beats
- Lentz, J. J., He, Y., & Townsend, J. T. (2014). A new perspective on binaural integration using response time methodology: super capacity revealed in conditions of binaural masking release. Frontiers in Human Neuroscience, 8, 641.
- Gao, X., Cao, H., Ming, D., Qi, H., Wang, X., Wang, X., … & Zhou, P. (2014). Analysis of EEG activity in response to binaural beats with different frequencies. International Journal of Psychophysiology, 94(3), 399-406.
- Isik, B. K., Esen, A., Büyükerkmen, B., Kilinc, A., & Menziletoglu, D. (2017). Effectiveness of binaural beats in reducing preoperative dental anxiety. British Journal of Oral and Maxillofacial Surgery, 55(6), 571-574.
- Solca, M., Mottaz, A., & Guggisberg, A. G. (2016). Binaural beats increase interhemispheric alpha-band coherence between auditory cortices. Hearing research, 332, 233-237.
- Garcia-Argibay, M., Santed, M. A., & Reales, J. M. (2019). Binaural auditory beats affect long-term memory. Psychological research, 83(6), 1124-1136
- Buskila, Y., Bellot-Saez, A., & Morley, J. W. (2019). Generating brain waves, the power of astrocytes. Frontiers in neuroscience, 13, 1125.
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