When you are singing together in a group, you can really get in sync. Not like this:
Instead, when you're all together and singing something really powerful, you kind of get the feeling that you're in sync with each other. That something about you is on the same wavelength.
What if you were really ON the same wavelength? And what if that same wavelength was in your heart rate?
Vickhoff et al. "Music structure determines heart rate variability of singers" Frontiers in Psychology, 2013.
When you sing, a truly amazing number of biological things are going on. You're controlling your breathing, tone production, and your tune in relation to other people around you. But does what you sing change what's going on in your body? Can what you're singing, say, change what your heart is doing?
The authors of this study had the hypothesis that group singing would influence heart variability of individual singers, and that it would do it...in a group context. That all the singers in the group would have similar heart variations.
How exactly is this supposed to work? Well, when you think of singing, don't just think of the tempo of the music, think also of what singing entails. It's not like playing the piano, it involves really controlling your breathing as well as the notes you are singing. Anyone with choir experience (or experience playing wind instrument like the clarinet or trumpet) will tell you that you have to learn to write in "breathmarks", places in the music where you can breathe. When singing, these are often pretty regular, but also a little bit (or sometimes a good bit) further apart than natural breathing.
If you are controlling your breathing in this way, it means that your breathing can begin to exert control over your heartrate. Heart rate and breathing can affect each other, and so the slow, regular breathing with slow paced singing can change the heart rate variability.
Note, this is heart rate VARIABILITY, not just heart rate. Your heart rate is much more variable than most people think. Every time you exhale, for example, activation of the vagus nerve causes your heart rate to slow down a very little bit. When you inhale, this braking action is released and the heart rate speeds up again. The fluctuation here is heart rate variability, and it's constantly changing.
But if heart rate variability is controlled to some extent by the rate of your inhaling and exhaling, and if singing involves everyone inhaling and exhaling together...then group singing could affect group heart rate variability.
To test this, the authors took 15 18 year old kids and had them go through a series of exercises while they were recorded for heart rate and heart rate variability. First, they read something emotionally neutral (aka boring) for a few minutes, then they were told to hum. After the humming (5 minutes) at a collective tone, the students sang a hymn together, "Fairest Lord Jesus". And finally, they chanted a brief mantra together, seen below.
During all of these tasks, the students wore ear clips to record their heart rate variability.
From the individual heart rate variabilities of the students, the authors compiled frequency domains. These isolate the major frequencies of the heart rate variability in each subject, and from there you can see whether there is an average.
What you can see above are the major frequencies for the baseline (top left), humming (top right), singing (bottom left), and chanting (bottom right). You can see in the top two that the frequences are very variable. They can get an average but it's not relfective of the activity taking place. In the bottom two, however, you can see that the major frequences for each subject line up pretty well with the average. The chanting is particularly striking.
Through all of their studies, the authors found that heart rate variability synched up during group singing or chanting, as the breathing rates (which sadly, were only measured in a smaller group) were put into sync by the music.
The authors conclude that: "Singing can be viewed as initiating the work
of a vagal pump, sending relaxing waves through the choir."
That seems a bit overly dramatic to me (especially the bit about relaxing waves through the choir). But it's clear that the heart rate variability is more in sync during singing, and that this is probably due to the synchronous breathing..
There are some things about the study that I think could have been done better. The pieces they picked to sing were well known, and also both slow and relaxing. One was "Fairest Lord Jesus", which is a pretty typical hymn. Slow. Relaxing.
(Zzzzz. Give me some Vittoria's O Magnum Mysterium any day.)
The other thing they were required to sing was a meditative repetition. While these are both fine, they are both at the relaxing end of the spectrum for tempo. And not just tempo. The hymn is well known and probably positively associated for the people who were singing it, and the meditation was the phrase "just relax". Both of these things are probably really...relaxing. What if they had to sing something that was slow...and intense? Like Lotti's Crucifixus or Mozart's Lacrimosa? Not only that, if group singing at a slow pace caused slower heart rate variation...would faster singing do the opposite? If so, then maybe only singing the hymns is really good for you. :) But the faster songs were not tested. I would have been interested to see them test this with new songs the participants were not yet exposed to, say teaching them a new song to sing together, or maybe having them learn a new song alone before coming in to sing it together in the lab. Songs that people didn't already know might be a better test than songs they already know...which already have associations and memories along with them. I also think they should have tried with a mantra that...didn't involve relaxing. Neutral words at least, in an effort to get rid of suggestion.
The numbers tested (only 18 were heart monitored) are also pretty small, probably they could have gotten better results with a larger number of people. The mantra produced pretty high synchronicity, but the hymn, much less so. Larger numbers might have helped this. I also noticed that there weren't really any statistics to compare one task to another. The statistics were listed in the text, but I would have liked to have seen the graphs comparing the different conditions, so I could see more clearly what they were comparing.
Also, The authors measure breathing (in a small subset of 5) and heartrate, and conclude that the breathing that is in sync is causing the heart rate variability to sync up as well. That may be true, but you can't really prove the cause there. But actually, there is an easy TO prove the cause. You need to have the group sing, divide them up into two or more groups...and give them different places to breathe in the music. Do the participants' heart rates sync up with similar breathers and not with dissimilar ones? That would help show that the breathing is indeed the cause of the heart rate sync.
The authors also talk in the discussion about how the group singing might have promoted a "we" perspective through group action, as the people were all singing the same piece. While that might be the case, the study definitely did not address how the people FELT about their collective sense of purpose or sense of "we". Really, there are a lot of conclusions in this study that I think could have been better supported.
But you CAN say that the shared action produced similar biological responses in the group of people. If you chant or sing in time, the rest of your body goes along, and if other people are doing it too, it means that you are really in sync.
Vickhoff et al. "Music structure determines heart rate variability of singers" Frontiers in Psychology, 2013. DOI.