On a warm summer afternoon in Zurich's Münsterhof, a young man sits with his shirt sleeves rolled up in front of an instrument that looks as if a UFO had landed. As soon as his fingertips touch the shimmering steel dome, a ribbon of sound unfolds, hovering between glockenspiel, harp, and distant temple music. Passersby, who were just checking their phones, pause. Some close their eyes. Others unconsciously shake their heads, as if an invisible cord were pulling both hemispheres of their brains into the same orbit.
The idea of “crossed wires” – and why rhythm is involved
Neuropsychologists speak of hemisphere synchronization when electrical signals in the left and right hemispheres of the brain not only appear similar, but oscillate almost in unison. Such synchronizations occur in flow states—when climbing, meditating, or making music. A high-speed neural tunnel connects the two sides: the corpus callosum. As early as the mid-1990s, a team led by neurologist Gottfried Schlaug discovered that this fiber bundle is significantly broader in professional musicians—especially those who began playing before the age of seven—than in non-musicians: more pathways, less congestion.
A quarter of a century later, a research group at Ruhr University Bochum specifically studied drummers. Twenty professionals, with an average of seventeen years of drumming experience, underwent MRI scans. The result: In the anterior part of the corpus callosum, they found fewer but thicker nerve fibers – as if nature had removed some secondary strands to strengthen the main pathway. The thicker cables directly correlated with precision in the drum test. The underlying hypothesis fits with the lived experience of many musicians: Those who repeatedly practice complex, bimanual patterns not only train their fingers and forearms, but also the bandwidth between brain regions.
This is precisely where a second concept comes into play, one that current neuroscience is increasingly defining: entrainment. This refers to the tendency of biological systems to adapt to external rhythms—from brain waves to heart rate to breathing. Not only mechanical systems like Huygens' pendulum clocks synchronize; neural circuits also reflect external impulses. The nexus of both ideas—hemispheric synchronization and entrainment—lies in music.
Hitchhiking through the corpus callosum
The magical timing attributed to drummers is created by movements that continually cross the body's midline: right hand to left, left hand to right—sometimes synchronized, sometimes offset. These "midline crossings" are considered to be gymnastics for the fibers between the hemispheres. In one case study, a 12-year-old boy with a congenital corpus callosum defect improved his balance, coordination, and even his social skills after a year of therapeutic drumming sessions.
The handpan forces a related, gentler choreography. Where a drummer throws sticks over tom-toms, the handpan player spirals around the middle note, often diagonally, with the index, ring, and middle fingers. Here, too, the hands work asynchronously—one pattern taps triplets, the other stomps duplets—but the sound remains mellow, almost inhalable. Listeners sense rhythm and harmony in the same breath; players couple both hands to a common, yet offset, grid. The effect: The brain is forced to integrate two divergent, yet coupled, time signatures—a kind of mountainous tandem ride.
What organizes sound in the body
EEG studies show that slow, regular impulses, particularly in the delta and theta ranges, trigger entrainment—waves that mark relaxed, sleep-like states. Music can amplify these rhythms and shift physiological processes: deepening relaxation, reducing pain perception, and promoting concentration. At the same time, changes beyond the brain can be measured. For example, rhythmic biofeedback often increases heart rate variability—a marker of parasympathetic activation, the "rest and digest" branch of our nervous system.
The handpan, in particular, which combines a percussive pulse with a floating reverberation, seems to hit a sweet spot here: The attack structures time, the reverberation expands it. For the brain, this isn't a contradiction, but rather an invitation to link internal oscillations to external patterns – prefrontal (attention, self-regulation), limbic (emotion), and motor (timing).
Between evidence and euphoria
Of course, the handpan is no magic bullet. There's plenty of evidence that drumming can lower blood pressure or promote anxiolysis, but reliable EEG protocols specifically for the handpan are still rare. The Bochum Drummer Study included twenty participants; Schlaug's corpus callosum work shows correlations, not causation. And even if connectivity increases, does it remain after six weeks of the workshop, or does it take years? Furthermore, entrainment isn't a one-size-fits-all tool. Subjective musical taste, early childhood influences, and cultural contexts all modulate the effect. What one person experiences as calming leaves another cold.
Nevertheless, sober pragmatism is worthwhile: When sound acts as a tempo-setter, it can be used specifically – in pain management, trauma therapy, or palliative care. Initial findings indicate that rhythmically structured music can reduce pain, not only through distraction, but also through a kind of neural reorganization. The handpan offers excellent conditions for this: easy playability, a rich overtone spectrum, and a natural invitation to bimanual patterns.
Two rooms, one principle
Back at Münsterhof, the set ends with a gentle palm strumming, the metal exhales. Coins clink, someone says thank you. The listeners stretch as if they've awakened from a shared dream. Perhaps this is the most inconspicuous form of hemisphere synchronization: alien minds, synchronously nourished by the same sound waves, move on in unison for a moment. Whether the left cortex finds this poetic or the right cortex seeks to explain it logically is secondary. What matters is that both listen—and that the rhythm from the outside governs the inner one. Entrainment and hemisphere synchronization are not opposites, but two perspectives on the same experience: We are not made for isolation, but for connection. In sound, this connection becomes physically tangible.
Further reading
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Thaut, MH, McIntosh, GC, & Hoemberg, V. (2015).
Neurobiological foundations of neurologic music therapy: rhythmic entrainment and the human brain.
Frontiers in Psychology, 6, 1185 -
Nozaradan, S., Peretz, I., & Mouraux, A. (2012).
Selective neural entrainment to the beat and meter embedded in a musical rhythm .
The Journal of Neuroscience, 32(49), 17572-17581.
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Large, E. W., & Snyder, J. S. (2009).
Pulse and meter as neural resonance.
Annals of the New York Academy of Sciences, 1169, 46-57.
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Zatorre, R. J., Chen, J. L., & Penhune, V. B. (2007).
When the brain plays music: auditory–motor interactions in music perception and production.
Nature Reviews Neuroscience, 8(7), 547–558.
