Playing good music for science is not something you get to do every day, but that’s exactly what neuroscientist Daniel Cameron from McMaster University did in a recent study. “We wanted to understand why people move to music,” Cameron says.

The researcher is a trained drummer and most of his research focuses on musical rhythm — the part of music that makes us want to synchronize our movements to it; basically what gives music its “dance feel.” But Cameron wanted to see whether the bass you can’t hear also plays a role in how danceable a tune is.

“We know from other research that the low frequencies in music are associated with our urge to move to music but we didn’t know if there is a real-world effect. If we added more bass, would people dance more?”

Drop the bass

Cameron conducts research at a unique facility called the McMaster LIVELab, a research theater equipped with a 3D motion capture as well as a specialized sound system that can replicate various concert environments and speakers that produce extremely low frequencies — “so low they were undetectable to the human ear,” McMaster told ZME Science.

“It’s a performance theatre AND a research laboratory. So, we can host amazing concerts and measure all kinds of things from the performers and audience members,” Cameron says.

Cameron and colleagues recruited participants to attend a concert at the LIVELab. They also recruited an electronic music duo called Orphx, known for their techno, industrial, and experimental music. The concertgoers were equipped with motion-tracking sensors that followed their dance moves and were also asked to fill out forms before and after the event.

“These forms were used to ensure the sound was undetectable, measure concert enjoyment, and examine how the music felt physically,” Cameron says. But other than this, it was pretty much a normal concert at a normal venue.

There was still a twist in the music though. During the concert, the researchers used special very-low-frequency speakers to produce low-bass sounds. The bass was turned on and off every 2.5 minutes, and the participants didn’t know when the speakers were coming on and off.

“Whether a certain frequency is audible or not depends on how loud it’s presented, as well as whether other sounds are present,” the researcher explained to ZME Science. “In this case, we believe the very-low bass we added wasn’t audible because we presented that part of the sound at a low level and it was in the context of loud music which ‘masked’ the very-low bass. The participants at the concert gave us some information about their subjective impressions, which indicated that they didn’t think the feeling of the bass at this concert was different from any other (the very-low frequency speakers we used are rarely used in concerts).”

“But more persuasively, we did a follow-up experiment in which a group of people who didn’t attend the concert compared pairs of audio excerpts from the concert. There was always one pair that was identical and one pair that differed—and the difference was always that the very-low frequencies were present/absent. We asked them to identify which pairs differed, and people could not tell—they were right around chance performance (just below 50%).”

The team found that overall, the amount of dancing increased by 12% when the low bass was on. But it’s not clear why this was happening. Still, Cameron has some ideas and speculates that the physical processes at work are those that link the neurological connections between music and movement.

“We suspect that these low frequencies are increasing movement vigor through the vestibular and tactile systems. The vestibular system (the mechanisms in our inner ear) is how we sense our position and movement in space, and we use it to balance. This system has low-level and direct connection to the brain’s motor system—the brain structures that control our movements. Low-frequency sound can stimulate the vestibular system, and so we think this pathway might be part of what’s underlying the effect we found.”

Another example of this is at loud concerts: if you’ve ever been at a loud concert, in the front (or just close to very loud speakers), you may have heard the vibrations in your chest, pounding and vibrating through your body. This may be another way that these low frequencies tap into our motor system and drive movement.

But we don’t know for sure yet, and that’s what Cameron and colleagues want to figure out in future research. In the meantime, if you’re having a party and want people to dance, playing some tunes with low bass may not be a bad idea.

The study has been published in Current Biology.