My research into underwater soundscapes has revealed an uncomfortable fact. In the estimated half-a-million ponds in the British countryside1 (that’s not including the two million or so small garden ponds), we can listen to sounds that most people can’t explain. And some of these sounds must have existed before humans, or any other creature for that matter, walked the Earth.
Plants first made their appearance on Earth in the Cambrian era circa. 530 million years ago (ref needed). During the process of photosynthesis, gases are released from the stomata of plants. In the case of aquatic plants these gases form discrete bubbles which can be counted to demonstrate plant stress (ref needed). They can also be heard using a hydrophone. It is one of the most distinctive and exciting sounds to hear underwater and never fails to impress participants in my Sonic Pond Dipping sessions. Seemingly passive in our surroundings, plants are instantly revealed to be a living, biotic entity. Our experiences of time become aligned. The school books we’ve read about photosynthesis and the importance of plants for planetary balance becomes part of a lived experience.
I’ve been unable to uncover any research into any rhythmic variations that aquatic plants may produce when exposed to light. Could it be that species of plants have individual ‘voices’? Could future bioacoustic studies allow us to identify a plant simply by listening? These are experiments which I am in the process of setting up through scientific collaborations with laboratory access.
So, what do aquatic plants sound like? To my ears, they are the time-keepers of our ponds, streams, and lakes. During daylight they lay down a persistent beats. Sometimes theses can last for hours, like a ritualistic ceremony to the bringer of light whose rays shine brightly through the watery firmament, not far above. Some species have an arching sound that modulates pitch like a whining oscillator. Others produce a wooden knocking sound that will incrementally slow down or speed up, like a DJ who subtly changes the energy on the dance floor. Sporadically, a burst of gaseous exchange causes an unexpected squeal, punctuating the soundscape (and maybe arousing a snigger…). Each plant seems to be guided by its own inner tempo, resulting in a highly polyrhythmic atmosphere. This is ‘time, no changes2‘ for an aquatic audience. It makes me wonder what role these plants have played in our understanding of rhythms as a fundamental property of human life.
The study of plants detecting and responding to sound has been coined ‘phytoacoustics3‘. These studies also crossover into ideas of plant sentience – new to science but with a long history in arts and cultures (refs needed).
In July 2024 I visited a section of the River Wear in County Durham with movement artist Scarlet Sumagr. Arriving early on a clear, sunny lunchtime, I positioned some hydrophones and assumed my listening position. Almost immediately I was pleasantly surprised to note some ‘new’ sounds – something akin to a bird chirping, although none were around (I removed the headphones on multiple occasions to double-check). Upon Scarlet’s arrival my headphones were passed over and the now familiar look, a cross between bewilderment, awe and excitement, shone across their face. Tuning into the aquatic soundscape, Scarlet almost immediately began to respond through bodily movements. I observed, as an outsider. Scarlet had taken a deep-dive, eyes closed, bare feet dangling in the clear water, headphones providing extra distance from the familiar sounds of our terrestrial soundscape.
After 5 minutes, Scarlet came up for air and described in lucid details the things heard. I’d not been privy to the sounds but hazarded a guess, listening back through the recording I’d made on the Sony PCM-M10. Plants, almost certainly, but also a melodic fragment which reminded me the peal of church bells (upload audio). Had the tolls of Durham Cathedral been ringing out, they’d be audible from where we sat. Could they be heard underwater? Perhaps these underwater percussionists were branching out and beginning to imitate extraneous sounds…
We placed an underwater camera in the shallow water, facing upwards, to view Scarlet’s improvisations from beneath the surface. A reversed aquarium4, the human gazing out. The movements of small fish merge with those of the human to create a multispecies collaboration, dancing to the sound of aquatic plants whose rhythms have gone unnoticed from millennia.
References:
de la Haye, D. Sumagr, S. (2024) In The Flow . URL: https://youtu.be/mkRCVQJIpGU?si=WeS_g1splH83Gfld
- Biggs, J. Williams, P. (2024) Ponds, Pools and Puddles. Collins New Naturalist Library, p.42 ↩︎
- See Ornette Coleman, Free Jazz ↩︎
- de Melo, H.C. (2023) Plants detect and respond to sounds. Planta 257, 55. https://doi.org/10.1007/s00425-023-04088-1 ↩︎
- See – Cohen, M. (2022). The Underwater Eye: How the Movie Camera Opened the Depths and Unleashed New Realms of Fantasy. Princeton University Press. https://doi.org/10.2307/j.ctv1nj342q ↩︎