Walking can feel like running, especially amid the noise of the city. Underground, its roots unfurl in strict tendrils. Narrow, geometric, and lined by pulsing veins of electricity. My train was sludging from platform to platform, moving like clots. It is noisy to be here, cocooned amongst a hundred bodies—a cloud of their odours, rustles of morning anxiety—all held in the din of our “noise-cancelling” devices. The self-developed vacuum to the sensory overload of a commute. Within this bubble of our curated sound worlds, we internally chug through podcasts, playlists, and series, all while a man-made racket cloaks us. Encased in my earphones, I listen to a calming film score, using it to disassociate from the shrieks and grinds of metal and rubber snaking underground. The unintentional irony of it all is that our codependent relationship with earplugs and acoustic devices has shielded us from actually hearing one another. 

When I am eventually released from this ceramic-tiled root system, I pace up concrete stairs, my heart ablaze with the adrenaline of wishing to be anywhere but contained beneath earth. But I keep my earphones in. Even above ground, I keep the soundtrack going, obstructing myself from the overwhelming soundscape of the city, its machines and its human inhabitants. It is human activity that consumes our imagination of noise, and with that, the assumption that all other life that shuffles beneath our feet does so blindly and silently.

Yet, we have long been aware that proximity to nature and its tranquillity, in sound, vision and scent, it can offer can greatly affect our mood and perspectives of life. Across cultures, traditions like Japan’s Shinrin-Yoku (forest bathing) or Italy’s passeggiata (evening walks) celebrate the simple act of walking and attuning ourselves to nature’s rhythms. These practices, whether explicitly mindful or subtly felt, reconnect us to a slower pace of existing. We find ourselves in contact with a different expression of time—ecological and geological. To walk through forests is to reconnect with earth and self. To walk through forests is to be humbled by the swiftness of human life. When encountered beyond the chaos of a tempest, nature can ground us emotionally and physiologically. 

In return for the care nature may offer us, we should be inclined to consider other modes of conservation. To restrict research and policy to only what we can see may not provide us with a holistic grasp of ecological wellbeing. We are now able to monitor biodiversity through sound. Acoustic ecology (or ecoacoustics) is the study of the relationship between living beings and their sonic environment’. A key example of work in this field is Sound Forest Lab. Sound Forest Lab is  a research project that documents the sonic identity of the world’s forests. Their research establishes an acoustic biodiversity baseline, a “sonic time-capsule,” of the diversity of noise. To simplify what acoustic monitoring indicates for ecological health, the greater the diversity in sound, the greater the biodiversity. 

It is from listening to forests that I ponder what it means for acoustic biodiversity for the other half of terrestrial life: the soil and below.

I like to imagine soil as a membrane. A skin-like veil between the life that flourishes on the surface and the microscopic bustle of subterranean living.

The ecological interconnectedness that happens above ground must in some way emerge from below and with growing interest in acoustic technology and monitoring, we can carefully listen to the Earth. 

Soil is not silent. It is the foundation of terrestrial life, the stage upon which the cycles of death and rebirth unfold. Beneath our feet lies a complex ecosystem teeming with life, where nutrients are harvested by fungi and microbes, fuelling the growth of plants, fungi, and animals alike.

In just a tablespoon of soil, there are an estimated 50 billion microbes and over 10,000 distinct species, and it ‘contains more life than there are humans on Earth’.

This astonishing biodiversity sustains not just the plants we see but the intricate web of life that feeds us, provides oxygen, and stabilises our environment. But this intensity of life is not only invisible to the naked eye—it is inaudible to the human ear.

The idea of listening to soil may seem strange, or even pointless, at first. The human ear can only detect sounds between 20 and 20 000 Hz, a range that diminishes with age or injury. In the face of these limitations, technology allows us to “hear” beyond this spectrum. Using microphones, sensors and software that visualises soundwaves, researchers can capture the subtle vibrations and signals emitted by life in soil. In fact, it is an act that is not so foreign. Since the 19th century, we have used seismographs to record and, in a sense, listen to the Earth’s subterranean movements. A seismic wave is a wave of acoustic energy, making seismographs visual records of acoustic data. On the other end of the scale, advancements in microphones and spectrogram software allow us to see and sonify the smallest of sounds. 

An example comes from ongoing experiments to biosonify mycelium. Mycelium are the fine root-like structures of fungi. Threading through soil a mycelium strand, each approximately a fifth of the width of a human hair, is part of a vast underground network often referred to as the “Wood Wide Web.” This network connects plants, enabling them to exchange nutrients and even warnings about pests, making up between 20 to 30% of soil biomass. In a teaspoon of soil, untangled mycelium can stretch between 100 and 10 km. If mycelium is a network that can be used for some form of communication between organisms, there must be a way of monitoring. Although we lack the knowledge and technology to fully grasp how complex this system could be or what forms of communication it may be, experiments measuring spontaneous electrical low-frequency oscillations in mycelium could open a way to microscopic listening.  If oscillations (and vibrations) are present, then we are able to translate this data into sound. Beneath our feet is rich noise we are only just attempting to understand.

From these forms of micro-listening, we are beginning to explore soil restoration and conservation from an acoustic perspective. Dr. Jake M. Robinson, a microbial ecologist, deployed sound equipment to listen to soil in different conditions—healthy, degraded, and restored. Like the acoustic baseline biodiversity monitoring of forests, his research indicated that healthy soil produces a richer, more complex range of sounds. Degraded soil, on the other hand, lacked the acoustic complexity that was present in revegetated soil plots. This sensory form of research offers a new way to measure soil health—not just through its chemical composition but through soundscape. Therefore, if we shift our collective imagination of dirt and think of the soil as alive, its health must matter. Dehydrated, polluted, or compacted soil cannot nurture life. Scientists have long assessed soil health through physical and chemical tests, but now if we are considering more sensory approaches, we can listen to measure its vitality and, by extension, our vitality. 

Listening to soil is more than a scientific curiosity; it is a call to action.

Healthy soil is essential for food production, carbon sequestration, and water filtration. Yet, modern agriculture, deforestation, and urbanisation have left large swathes of soil degraded. If we ignore the signals of soil, we risk silencing the very foundation of terrestrial ecosystems. By “hearing” soil, we can better understand the impacts of our way of living and make informed decisions about maintenance and restoration. For instance, perhaps acoustic monitoring can be deployed to assess the effects of different agricultural practices, such as cover cropping or reduced tillage, on soil health. Conservationists could track the progress of rewilding efforts. Even urban planners could evaluate the hidden ecosystems beneath city parks and green spaces.

Pauline Oliveros, the experimental composer, once wrote, “Walk so silently that the bottom of your feet become ears.” Her words, written half a century ago, remind us that listening is not simply hearing but a practice of attunement—of noticing what often lies buried beneath the noise of our days.

To meet with Mother Nature, we must first learn to listen to her, all of her. Soil can chant a story of nourishment, decay, and renewal. If the earth beneath us truly fell quiet, so would we. Perhaps it is time we walk in Olivero’s quiet steps, letting our soles listen.

Words by Victoria Pham

Photo by Jacob Whittaker