how connection developsSinging a phrase together gives people more than a shared melody. It also gives them places to breathe. In a 2013 study, Björn Vickhoff and colleagues found that the structure of what people sang was reflected in the recurring rises and falls of their heart rates.
A repeated phrase with a regular breathing interval produced a common pattern across singers. Humming, where each person could take a breath whenever needed, produced regular patterns within individuals that differed from one person to another. A familiar hymn produced a more complex pattern related to its phrases.
The comparison makes a physical aspect of singing together more understandable. Musical timing can coordinate breathing, and breathing is coupled with changes in heart rate. The degree and kind of coordination depend on what is being sung.
Three ways to organize a breath
The group study involved fifteen healthy eighteen-year-olds with previous choir experience. Technical problems left eleven recordings suitable for analysis. Participants sat together and performed three five-minute tasks, with silent reading providing a baseline.
First, they hummed a shared tone, taking breaths when they needed them. Next, they sang a familiar hymn with piano accompaniment. Finally, they sang a short phrase composed for the experiment, with instructions to breathe only between repetitions. Each complete phrase-and-breath cycle lasted about ten seconds.
These tasks provided different levels of structure. Humming offered no shared timetable for breathing. The hymn's melody and phrases suggested places to breathe while allowing some variation. The repeated phrase supplied a much more uniform cycle.
The tasks occurred in a fixed order, so the experiment did not fully separate the effects of the music from possible order effects. Within that design, the detailed differences between conditions closely followed their musical structure.
A regular rhythm within each singer
Heart rate changes continually rather than remaining perfectly constant. The researchers examined both the amount of variation and the timing of recurring changes. These describe different features of the signal.
Humming made each person's pattern of heart-rate acceleration and deceleration more regular than the reading baseline. It did not produce the same dominant rhythm in everyone. Because people chose their own moments to breathe, one person's recurring pattern could be faster or slower than another's.
The contrast also appeared in how much heart-rate variability changed. Humming made its timing more regular without significantly increasing the measure of variation used in the group study. The hymn increased that variation even though its pattern was less dominated by one repeating cycle. A more regular signal and a larger amount of variation were different results, not two ways of describing the same benefit.
This is an important distinction for understanding shared activities. Everyone can be making a sound together while the underlying timing of breathing remains individual. Participation in the same task does not automatically mean that every bodily rhythm is synchronized.
The hymn produced a different result. Heart-rate variation contained common frequencies across singers, even though the pattern was more complex than a single repeated cycle. The authors related that complexity to the different lengths and arrangements of the hymn's musical phrases.
During the specially composed repeated phrase, the common rhythm was particularly clear. Heart-rate changes had a prominent cycle of about ten seconds across participants, matching the instructed timing of breathing. The music supplied a regular structure that appeared in the physiological records.
Following the link through breathing
To examine the mechanism more closely, the researchers conducted an additional study with five other participants. This time they recorded breathing alongside heart activity using more precise equipment. The participants sang together, but the equipment recorded one person at a time across repeated performances of the same sequence.
That detail sets a boundary on the evidence. The additional recordings could show how individuals' breathing and heart-rate patterns related to the same musical timetable. They were not simultaneous records of all five hearts during one shared performance.
The records showed a close relationship between breathing and heart-rate variation. This relationship is known as respiratory sinus arrhythmia. In ordinary terms, heart rate tends to increase during inhalation and decrease during exhalation. A structured breathing pattern can therefore produce a corresponding pattern in the changing intervals between heartbeats.
During humming, breathing and heart-rate cycles were coupled within individuals but remained different across individuals. The hymn produced several recurring components related to its musical organization. The regular repeated phrase produced a much more concentrated common cycle.
The hymn's longer structure was visible as well. An overarching pattern appeared around longer musical sections, reflecting differences in breathing depth at those points. The authors explicitly cautioned that this did not mean singers were simply taking one breath every twenty seconds. The music organized layers of the breathing pattern, including the depth as well as the timing of breaths.
What synchronization means here
The group recordings showed shared frequencies of heart-rate variation during the hymn and repeated phrase. The more precise additional recordings also showed more stable relationships in the timing of these fluctuations when aligned to the musical sequence.
These results concern recurring acceleration and deceleration. They do not establish that every individual heartbeat occurred at exactly the same instant in every singer. Two people can share a pattern of speeding up and slowing down while having different average heart rates and different individual beats.
The authors' phase analyses also distinguished a stable timing relationship from perfect alignment. A recurring difference between two patterns can remain stable without disappearing. Describing all the hearts as beating identically would lose that distinction.
The small additional study found stronger coupling between breathing and heart-rate variation during the singing conditions than during the baseline. It did not establish statistically reliable differences between every form of singing on that measure. Skin conductance and finger temperature also produced no significant findings.
The way breathing was organized also affected how the measurements could be interpreted. One commonly used ratio divides heart-rate variation into lower and higher frequency bands. Here, the slow breathing moved respiratory variation into the lower band, making that ratio unsuitable as a straightforward measure of vagal activity. The musical task helped explain the signal. The number alone could not establish how calm or connected a singer felt.
Shared timing and the experience of singing together
The authors discussed possible implications for wellbeing, communication, and collective action. Those ideas went beyond the outcomes directly measured here. The study did not assess whether participants felt closer, became more cooperative, or experienced lasting health changes. It also did not compare singing together with singing alone.
Its contribution is a more precise account of how the organization of a shared activity reaches into bodily timing. The melody provides phrase lengths. Those phrases influence breathing. Breathing is linked with heart-rate fluctuations. When the musical structure is shared and regular, a common pattern can emerge among the singers.
Different forms of singing leave different amounts of room for individual timing. A held tone, a varied hymn, and a repeated phrase are therefore physiologically different activities as well as different musical experiences.
Sources
Vickhoff, B., Malmgren, H., Åström, R., Nyberg, G., Ekström, S.-R., Engwall, M., Snygg, J., Nilsson, M., & Jörnsten, R. (2013). Music structure determines heart rate variability of singers. Frontiers in Psychology, 4, 334. Read the full paper.
Vickhoff, B., Malmgren, H., Åström, R., Nyberg, G. F., Ekström, S.-R., Engwall, M., Snygg, J., Nilsson, M., & Jörnsten, R. (2013). Erratum: Music structure determines heart rate variability of singers. Frontiers in Psychology, 4, 599. Corrects the ordering of hymn and mantra labels in four figures.