Low frequency bass boosts boogieing
This is an excerpt from a special concert recently performed by Canadian techno duo Orphx. The concert took place at the LiveLab facility at McMaster University in Canada a short while ago. Dan Cameron, post doctoral research fellow at McMaster, uses this music venue with a difference to pull off some pretty unique research. As well as being a neuroscientist, Dan is a keen drummer. He’s interested in the way music makes us want to dance - something of an evolutionary curiosity. The LiveLab hosts genuine concerts and is equipped with microphones and speakers designed to be able to change the acoustics of the concert hall on a whim. They can measure brain activity from the audience members and the performers there using small sensors attached to their heads and also have motion capture technology to measure their movements. I asked what all this tech was teaching us about techno…
Dan - So I've always been interested in rhythm and what types of rhythms make us feel the strong sense of a beat that we can synchronise our movements to. But there's been another component and that's the bass - the low frequencies in music. And we know from anecdotal reports that people who like to go to electronic dance music concerts, they feel immersed in the base. It affects their body, it feels good, it makes them want to dance. And we know from experimental work that there are associations between bass, or low frequencies, and movement and movement timing in particular. But kind of in the same way that with a medical drug you need to test not just if it affects the body or the tissue in the way that you expect, but is there a clinically relevant effect? Does it actually change people's outcomes and lives?
Dan - We didn't know if there was a real world effect. Now, for this study, we were having a concert from the electronic music duo called Orphx. And people were paying to come, they were buying tickets and we thought, "we can do an experiment here as well on bass and movement." So we asked people if they wanted to volunteer for this experiment and all they needed to do was put a really simple headband on their head that had a motion capture sensor on it. And then they went and enjoyed the concert and they danced. And the thing we did to test whether bass affects their dancing is we had these specialised speakers, these very low frequency speakers that play bass frequencies that are really low. Most speakers are not able to play these and they're not generally part of the musical experience. We needed people to be unaware of when we were turning these speakers on and off. When they were on, they were at a pretty subtle level, and we had a couple of pieces of evidence afterwards that really did indicate to us that people couldn't detect when these extra low frequencies were on. What we found was that, by using motion capture, we could track everyone's movements. When the very low frequencies were present, when those speakers were on, people danced about 12% more than when they were off.
James - And what do you attribute that increased dance-ability of the music to, even if it can't be audibly heard?
Dan - So this is speculation because we didn't test these mechanisms, but we have an idea from other work that's out there. And we think that it's not just the auditory system (our hearing) that processes the music and especially these low frequencies, but we think that our tactile system (our sense of touch) and our vestibular system (our inner ear, that part of our body and sensory system that processes our sense of balance and where we are in space.) We know that low frequencies, if they're sufficiently loud, can stimulate the mechanoreceptors on our skin and in our body. So if you've been to a concert and you stand very close to a loud speaker, you can feel it kind of rattling in your chest maybe, or on your skin. That's the sound vibrations. The vibrations in the air are stimulating our sense of touch. And we know that our vestibular system is also important in rhythm perception generally - music perception and our sense of moving in time with music. We can change people's perception by having their vestibular system stimulated at a particular rate. If they bounce along to music, that'll change how they hear that music later. But both of those systems, our sense of touch and our sense of balance, are strongly connected in the brain to our motor system - the parts of the brain that control our ability to move and to control our movements.
James - How did you account for the fact that music naturally has these peaks and troughs - parts of the song that are naturally going to encourage more of an energetic response and parts where listeners are invited to catch their breath, perhaps. How do you know that these parts of the music didn't line up necessarily with when you were using these low frequency bass sounds that people can't actually hear?
Dan - We can't control for that perfectly because this was an ecologically valid, real world experiment. It was a concert; the musicians were performing, people were there enjoying it and dancing. But what we could do is spread out these periods where the speakers were on the extra low frequency. We would turn them on for two and a half minutes, then we would turn them off for two and a half minutes - on for two and a half minutes, off for two and a half minutes.
James - So you saw what you describe as fairly unanimous results across the participants, and you mentioned that there was a 12% increase in movement. Is that, would you argue, pretty significant? Or will we need more of these types of studies to gauge what your numbers really mean?
Dan - That's hard for me to say. We were surprised and pleased at how robust the effect was, how reliable it was overall. But is there a facilitatory effect of the low frequency stimulation that we provided? Does that increase the social cohesion effects as well? Can we see that and how does that change? But yes, absolutely. We want to see the future research that builds from this and connects to this to better understand how this works in the real world.