Good Vibrations: Inaudible Sounds Can Increase Dancing

Posted by Dalia Saklaway on March 30, 2023 in Music, Neuroscience | Leave a comment

The year is 2022, and you’re standing in a sea of people in the hot Coachella Valley. Just as your legs are about to give out from standing for too long, Swedish House Mafia enters the stage with a song that makes everyone start jumping and head banging. With every beat drop you dance harder and you move more. The music is so good that not only can you hear it, but you can feel it.

If you enjoy listening to music, you may have experienced something similar when you can feel the music, or when the song is so good you can’t help but to dance or even just tap your foot. People have even reported that they have felt intense physical and physiological effects, especially when listening to music that specifically contained low-pitched bass sounds such as electronic dance music (EDM) [1]. EDM is a genre of music that features beats that are produced electronically and very low-pitched bass rhythms. What is that feeling that we get in our body when we listen to EDM or lower-pitched music in general, and what causes it? It turns out, based on a study by Daniel J. Cameron and others, that it is possible for low-pitched inaudible sounds to directly cause people to move and dance more even though they can’t even hear it. Humans have a hearing range from 20Hz to 20,000Hz, meaning humans can only hear and consciously detect sounds that have a frequency within this range [9]. The low-pitched inaudible sounds used in Cameron’s study were below 20Hz, which suggests that maybe there is a part of music that we really do feel.

All About That Bass

When one thinks of bass sounds or music, they may think of very low-pitched sounds that they can almost feel vibrating within their body. Low-pitched bass sounds and high-pitched sounds are both sound waves, but one of the main things that distinguishes them is their frequency. The frequency of a sound wave refers to how often, or how frequently, the particles in the air surrounding us vibrate when a wave passes through them [2]. As depicted in the figure on the left, bass sounds that are low-pitched have a low frequency and high-pitched sounds have a high frequency. 

In previous studies about bass music and movement, it was discovered that lower frequency sounds that are audible cause people to move more [3]. The way that this was discovered was by having research participants listen to musical clips with higher and lower frequencies and then asking the participants to give it a “groove rating”. Groove has been defined as the urge or desire to move to music. Essentially, the participants were rating the musical clips based on how much groove they felt. The findings were that the groove rating and the groove of the participants tended to be higher when they were listening to the lower frequencies. It turns out, not all music can be as groovy as others!

Can U Feel It

Scientists Daniel J. Cameron and others wanted to take studying bass and movement a step further. Although it is known that low frequency bass music that one can hear can compel them to dance more, they questioned whether or not low frequency sounds that one cannot even hear could have the same effect. This study took place at a live electronic music concert by the duo Orphx, in which very low frequency (VLF) speakers were turned on and off throughout the concert [4]. The research participants and concert goers were asked to wear motion-capture marker headbands so that their movement during the concert could be studied. The VLF speakers were turned on and off every 2.5 minutes within the span of the 55 minutes that Orphx was performing, resulting in 18 segments of movement to analyze. As shown in Figure 1, the full audio of Orphx performing their music is continuous and the VLF speakers were turned on (vertical black block) and off as time passed during the concert. Cameron and his research team then calculated head movement speed for each participant during the 18 different segments and compared average normalized movement while VLF speakers were on vs. off. After this analysis they concluded that the research participants moved more, on average by about 12%, while VLF speakers were on. Based on this study, there were, in fact, inaudible low frequency sounds that directly caused people to dance more which proved that low-frequency stimulation can have an unconscious effect on movement and behavior.

On My Mind

Why do lower frequency sounds cause us to move more and what goes on in our brain when we hear them? Although there is more to be explored about this phenomenon, a theory that may explain why we have the strong urge to dance once we feel music has to do with our reward system. In this case, the low frequency sounds are the rewards which release chemicals, called neurotransmitters, in our brain that cause us to move more.

Another very likely explanation has to do with how sounds are processed by our brain, even those that we can’t necessarily hear. Music and sounds, such as these low frequency sounds that are being researched, are processed by the auditory, vestibular, and vibrotactile pathways. The auditory pathway includes the structures that make up the ear such as the outer, middle and inner ear, and the specific brain regions that process sounds such as the auditory cortex [5].

The vestibular system starts with the inner ear, which has fluid filled canals that are responsible for detecting changes in head movement, and ends in specific brain regions that process the information about the position and movement of the head, balance, and spatial awareness [6]. These fluid-filled, semi-circular canals in the inner ear are part of the vestibular apparatus as shown in Figure 2. The vestibular ganglions are neurons that send signals from the vestibular apparatus, in the inner ear, to the cerebellum, a region in our brain that process the information about balance and spatial awareness. Once our cerebellum processes this information, it elicits a motor response, also demonstrated in Figure 2. In the case of Cameron’s experiment, the motor response was an increase in dancing and movement.

The vibrotactile pathway sends information about the sense of touch to the brain through vibrations [7]. Receptors in the skin called Pacinian corpuscles are responsible for sensing vibrations and then sending signals to the brain in which the brain will process and recognize these vibrations as sensations of touch [8]. These Pacinian corpuscles are located underneath our skin in a layer called the hypodermis, as shown in Figure 3. Pacinian corpuscles sense information about vibration, such as sound vibrations at a concert, and send signals to a specific part of the brain called the parietal lobe (yellow region in Figure 4). The parietal lobe is the region of the brain that will process these vibrations as feelings of touch.

Since the low-frequency sounds used in Cameron’s experiment were inaudible, he and other researchers hypothesized that the effects of these unheard sounds on body movement most likely occurred via the vestibular and vibrotactile pathways [4]. These two systems are linked to and send signals to our motor system, telling our bodies to move. Additionally, knowing that low frequency sounds are processed in part by the vibrotactile pathway and knowing that the vibrotactile pathway allows us to recognize vibrations as sensations of touch, may largely explain why one may report that they feel music. 

I Like To Move It

Knowing that low-frequency sounds can increase movement is fascinating and valuable in many other aspects of peoples’ lives. A situation, for example, in which one would prefer to increase their movement, is when they are engaging in physical exercise. There is science based evidence that listening to music with low-frequency sounds can increase movement and dancing, so one can use this information to their advantage to be more active at the gym or during a run. Most of the time, spin or other fitness classes are blasting remixes, bass beats, or EDM, which we now know promotes an increase in movement. The genres of music that are the most associated with low-frequency sounds are EDM, house, bass, and dubstep. However, if you are not a fan of any of those music genres but you still want to take advantage of this phenomenon while working out, rap and rock are other genres of music that have low-frequency sounds as well.

Another instance in which low-frequency sounds can be applied, is in motor rehabilitation [10]. Motor rehabilitation is a method that is used to promote the learning of movement again or to regain motor function. Stroke, Parkinson’s, or traumatic injury patients are examples of people who do not have enough control of their motor functions and who would have to go through motor rehabilitation. Music based interventions for motor rehabilitation has been used for years, and research on low-frequency sounds and movement, like Cameron’s, not only confirms the effectiveness of music based interventions, but also provides new revolutionary insights on ways to improve it.

 

References

1. Jasen, Paul. “Low End Theory: Bass, Bodies and the Materiality of Sonic Experience (Bloomsbury, 2016).” Academia.edu, 22 Apr. 2015
2. “Physics Tutorial: Frequency and Period of a Wave.” The Physics Classroom, https://www.physicsclassroom.com/class/waves/Lesson-2/Frequency-and-Period-of-a-Wave. 
3. Stupacher, Jan, et al. “Audio Features Underlying Perceived Groove and Sensorimotor Synchronization in Music.” University of California Press, University of California Press, 1 June 2016, https://online.ucpress.edu/mp/article-abstract/33/5/571/92017/Audio-Features-Underlying-Perceived-Groove-and?redirectedFrom=fulltext. 
4. Cameron DJ;Dotov D;Flaten E;Bosnyak D;Hove MJ;Trainor LJ; “Undetectable Very-Low Frequency Sound Increases Dancing at a Live Concert.” CB, U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/36347227/. 
5. Peterson DC, Reddy V, Hamel RN. Neuroanatomy, Auditory Pathway. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532311/
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7. Malone PS, Eberhardt SP, Wimmer K, Sprouse C, Klein R, Glomb K, Scholl CA, Bokeria L, Cho P, Deco G, Jiang X, Bernstein LE, Riesenhuber M. Neural mechanisms of vibrotactile categorization. Hum Brain Mapp. 2019 Jul;40(10):3078-3090. doi: 10.1002/hbm.24581. Epub 2019 Mar 28. PMID: 30920706; PMCID: PMC6865665.
8. Germann C, Sutter R, Nanz D. Novel observations of Pacinian corpuscle distribution in the hands and feet based on high-resolution 7-T MRI in healthy volunteers. Skeletal Radiol. 2021 Jun;50(6):1249-1255. doi: 10.1007/s00256-020-03667-7. Epub 2020 Nov 6. PMID: 33156397; PMCID: PMC8035111.
9. Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. The Audible Spectrum. Available from: https://www.ncbi.nlm.nih.gov/books/NBK10924/
10. Braun Janzen T, Koshimori Y, Richard NM, Thaut MH. Rhythm and Music-Based Interventions in Motor Rehabilitation: Current Evidence and Future Perspectives. Front Hum Neurosci. 2022 Jan 17;15:789467. doi: 10.3389/fnhum.2021.789467. PMID: 35111007; PMCID: PMC8801707.