AV Quick Takes: Deep Bass Makes The Booty Shake

A fascinating article in the scientific journal Current Biology details a new study by researchers at McMaster University (a public research university in Hamilton, Ontario, Canada), which showed that the presence of very-low-frequency sound increased dancing at a live concert. That might not sound too surprising at first; dance music tends to have plenty of bass, and bass instruments like kick drums and bass guitars often provide the musical pulse that dictates how and when dancers move. But this study found that the presence of extreme low-frequency bass — frequencies so low that they can’t be heard by the human ear —  increased dancing. The researchers effectively turned a live electronic music concert into a lab study by introducing these frequencies using specialized subwoofers, and monitoring the crowd’s movements. The scientists found that people danced 11.8% more when the very-low-frequency bass was present. The study was part of a broader research effort to understand how different aspects of music influence the human body.

The explanation as to how “undetectable” low frequencies influence dancing is interesting. If you’ve ever experienced an infrasonic subwoofer (or an earthquake), you know that low-frequency sound is processed not only by auditory pathways, but also by vibrotactile and vestibular pathways. (Vibrotactile feedback is “feeling” sounds, such as the physical sensation of having your whole skeleton rattled by a Perlisten subwoofer. The vestibular system refers to those parts of the body, starting with the inner ear, that help us maintain postural balance and spatial orientation in response to changes in the environment.) The study found that the stimulation of these “non-auditory modalities,” in the context of a concert, increased what the researchers refer to as “groove” — the pleasurable urge to move to music.

The study’s head author, a neuroscientist named Daniel Cameron, conducts research at the McMaster LIVELab, a unique research theater that connects science with live performance. The theater is equipped with a Meyer sound system that can replicate various concert environments, and specialized subwoofers that can reproduce frequencies well below 20Hz. The theater also has 3D motion capture capability, which helps the researchers study the movement of the concertgoers. For this study, participants wore motion-sensing headbands during a performance by the electronic musical duo Orphx. Participants provided additional information before and after the event via surveys that helped to ensure that the low-frequency sound was indeed undetectable. Participants were also asked to rate how much they enjoyed the concert, and how the music felt physically.

I’m trained as a drummer, and most of my research career has been focused on the rhythmic aspects of music and how they make us move. Music is a biological curiosity – it doesn’t reproduce us; it doesn’t feed us; and it doesn’t shelter us, so why do humans like it and why do they like to move to it? The musicians were enthusiastic to participate because of their interest in this idea that bass can change how the music is experienced in a way that impacts movement. The study had high ecological validity, as this was a real musical and dance experience for people at a real live show. Very low frequencies may also affect vestibular sensitivity, adding to people’s experience of movement. Nailing down the brain mechanisms involved will require looking at the effects of low frequencies on the vestibular, tactile, and auditory pathways.

— Daniel Cameron, neuroscientist at McMaster University

Cameron and his team turned the extreme LF bass on and off every two minutes throughout the 45-minute concert, which helped control for the fact that certain sections of the performance might naturally promote more dancing than others. The 11.8% increase in dancing when the LF bass was on supports the notion that the bodily sensations of vibration, along with the interactions between the inner ear and the brain, have a close link to the human motor system. These complex physical processes are probably involved in the connection between music and movement at its most basic level, the researchers speculate.