Two or Three Confusions About Vibrations

Abstract

Road traffic noise is considered the largest contributor to excessive noise exposure levels in Europe. Central to this type of noise is what is called “rolling noise.” This article emerges from an ethnographic encounter with a group of individuals in Greater Paris who are protesting road traffic noise, not as noise, but as vibrations. But is there a difference between noise and vibration? Why are vibrations not included within noise regulations? Is it a question of sensation? Is there a sense of vibration? If STS has shown how objects of knowledge, the senses, and bodies are assembled in social, political, and technological configurations, this article describes how vibrations and their sensory experiences slip out of them. Through a brief ethnographic encounter and a historical narrative, this article is about two or three confusions: between noise and vibration, the senses, and confusion as a form of knowledge itself. It is interested in how the sensory knowledge of vibration blurs sensory categories and challenges the bodily model that environmental regulations rely on. While vibrations have opened up reflections on other ways of sensing, they also provide an opportunity to think with, and not against, confusion as a form of knowing in uncertainty.

How tired I am of stories, how tired I am of phrases that come down beautifully with all their feet on the ground!…What delights me then is the confusion, the height, the indifference and the fury. Great clouds always changing, and movement; something sulphurous and sinister, bowled up, helter-skelter; towering, trailing, broken off, lost, and I forgotten, minute, in a ditch. Of story, of design, I do not see a trace then.—Virginia Woolf, The Waves (2016, 171)

Introduction

I almost did not notice it (Figure 1). But once I had, more and more appeared. They were everywhere, increasing in frequency as I walked down the road. Posters attached to telephone poles, on tree trunks, wooden gates, and windows close to the street: LA D35 TER EN COLERE! NON AUX VIBRATIONS DES POIDS LOURDS SUR LES ZONES FRAGILES! ¹ It was also not until that moment, in late June, that I began to pay attention to the trucks and busses passing by on this residential road on the outskirts of Paris. Whish. Whish. Whish.

Figure 1.

These are posters related to a protest against vibrations from heavy vehicles in June 2023. They are attached to telephone poles and trees in a suburb of Paris, France. The slogans say that the road (“D35 TER”) and thus the residents along that road are furious. The lower sign on the left refers to a public meeting with public officials from the Seine-Saint-Denis department, the administrative district the road is located in, related to the upcoming redevelopment of this road (Source: Author).

But what does it mean to say no to vibrations and to protest against them?

I was in Paris to do research on environmental noise with a noise observatory, interested in how noise becomes, or resists becoming, an object of knowledge and a political concern within urban contexts. Following the acousticians to measurements of schoolyards and houses, into neighborhood and city council meetings, vibrations rarely came up. Or if they had, they were already transduced into registers associated with sound and noise.

In contrast, roads and their noise were often discussed. Road traffic in Paris, as in the rest of Europe, is the main contributor to noise pollution. In 2022, 227,913 Parisians (10.5 percent of the population) were exposed to harmful levels of road noise (Mairie de Paris 2023)—“harmful” insofar as the levels exceeded the threshold set by the World Health Organization and filtered through what has been established as the standards of human audibility. ² The most important source of road noise is what is called “rolling noise”—noise emitted due to the friction between tire and asphalt, ³ constituted through the deformation of the tire as it interacts with the texture of the road, which “produces vibrations in the tire carcass around the tire-road contact zone” (Pallas 1990, C2–785). It is a noise that is the result of traffic-induced vibrations. Encountering those posters against vibrations along the road confused me: Why protest vibrations and not noise? Is noise not also (partly) vibratory? Why do environmental noise policies and regulations not also include vibrations? ⁴ Is it because “vibrations” occur below the threshold of what the average human should hear, and is thus not legible within the established thresholds?

The risk of confusing vibration and noise is often emphasized in discussions of noise. Isabelle Maramotti (1999, 165; my translation), a psychologist who has studied environmental issues in cities, has written that “the resulting annoyance is often confused with the noise that accompanies these phenomena [vibrations] and is sometimes treated as a problem of acoustics.” In their handbook on community noise, Birgitta Berglund and Thomas Lindvall (1995, 64) write that the “perception of sound from 100 Hz down to about 2 Hz is a mixture of auditory and tactile sensations”—a mixture of sensations that points to the “combined effects” of noise and vibration. Vibrations below 100 Hz are referred to as low frequency noise or infrasound (below 20 Hz)—whose potential “audibility” is debated (Leventhall 2009; Schiavi, Rossi and Ruatta 2016) and resists being measured through the standard methods for measuring environmental noise.

This article is interested in this risk of confusing noise and vibration, the auditory and the tactile. It explores how this confusion can unsettle the “sensory regimes” (Howes 2023) or “regimes of perceptibility” (Murphy 2006) that undergird environmental noise regulations, drawing attention to how they rely upon a model of the body—a modern “bureaucratic body” (Jones 2006)—organized into clear and distinct categories of sensation. Here I examine the difficulty of regulating the senses, of decoupling the auditory from the tactile, and how sensory experiences do not always match these categories of sensation that guide environmental pollution regulations. To discuss this, the article draws on two threads of research in Science and Technology Studies (STS) and anthropology. On the one hand, it builds on the work in feminist STS that has long explored the effects of bodily models and metaphors in biology and psychology (Cowan and Rault 2022; Fox Keller 1995; Haraway 1990), questioning figures of the body as natural, individualized, or autonomous. A recent part of this thread incorporates discussions about pollution and exposure, the ways in which bodies are porous to and enmeshed with their environments (Alaimo 2016; Liboiron, Tironi and Calvillo 2018; Murphy 2000, 2006). These studies have described how the effects of pollution “dissolve” (Alaimo 2016) the boundaries between bodies and environments. Through the sense of vibration, this article extends this by threading through another strand of STS in relation to the sensory (Friedner and Helmreich 2012; Latour 2004; Pinch and Bijsterveld 2004; Shapin 2016; Tkaczyk, Mills and Hui 2020) in order to discuss the limits of the senses.

On the other hand, the article turns to research that has attended to the ephemeral and the fleeting, to phenomena that slip out of legibility and elude definition. This research has paid attention not only to indeterminate and elusive things, but to the methods, modes of attunement and relating, used to know them (Choy 2018; Peterson 2021). They have associated these things with what exceeds the human, whether “more than human,” environmental, or as more complicated hybrids, technical and artificial. To describe these shifty amalgams, they have also argued for new conceptual vocabularies and analytics that acknowledge the doubts and uncertainties that are also integral to the knowledge and forms of sensitivity used to grasp experiences and entities that elude and are “out of phase” with themselves (Walker 2021). Through concepts like “entanglement” (Tsing 2015), “atmosphere” (Choy 2018; Peterson 2021), “swirl” (Adams 2023), “muddle” (Ahmann 2024), “leakiness” (Anand 2015), or “slipperiness” (Law and Lien 2013), among others, they have sought to describe what challenges being fixed and known within stable ontological and epistemological categories based on clarity and certainty. Following this research, in this article I describe how vibrations resist analytic attempts to demarcate clear and distinct objects in the world, and, at the same time, the sensory organs that sense, perceive and know them. I am interested in how this risk of confusion within sensory experiences of vibrations can speak to the often indeterminate and unclear ways in which environmental phenomena are known.

This article explores two or three confusions about vibrations. It does this by returning to a brief ethnographic encounter with the protest against vibrations, and through a short history of the search for the sense of vibration—a sense situated somewhere between hearing and touch, ear and skin. Vibration, I argue, draws us into confusion between the senses, bodies and environments, and the challenge of turning sensory experiences into clear and distinct sensory categories. Rather than treating confusion as what requires clarification, as moments in which the senses deceive, or as a strategy for sowing doubt, uncertainty, and inaction (Auyero and Swistun 2009), this article reflects on the epistemic significance of confusion itself. It follows Michel Serres' (2008) notion of confusion as a form of sensory knowledge that does not analytically cut up experience into distinct categories, but allows for what is mixed-up, entangled, unanalyzed, and confused. Rather than resolving or explaining this confusion, the article holds in suspense the questions (and confusions) that experiences of vibration generate—to keep what Vinciane Despret (2021, 62) has called “the mobilizing power of the enigmatic” present in the text. As a result, this article does not offer closure or answers to the questions I had when I encountered the protesters, and which spur the history of the search for the sense of vibration. Is there a sense of vibration qua vibration? Or is it a mixture? Why is there a risk of confusing vibration with sound, of touch with hearing? And if vibration is confusion, what knowledge is borne from that?

Vibration as Potential

A rumble underfoot, the tremble of a building, a flutter across the skin, a buzz sometimes heard, sometimes felt. Vibrations are difficult to grasp. Conventionally defined as the oscillatory motions of bodies and the forces associated with them, vibrations are mechanical disturbances, sometimes periodic, and sometimes not. They come without form, as movements, that nevertheless rely on forms, matters, and bodies to appear. Depending on the rate of their oscillations, and the media that receives them, they take shape in different ways. But vibrations are also little events: vanishingly small, and most of the time, not noticed at all. They proliferate in the background of everyday life, shaking air and ground, infrastructures, ears, and bodies. If you look close enough, they blur the outlines of solid objects, unsettle stable foundations and classifications, connecting things and bodies invisibly across distances.

Vibrations permeate environments in excess of sense and sensor. The ecological psychologist James J. Gibson (1966, 16), in his discussion of perceptual systems, had charged vibration with potentiality, an array of ambient energy that shakes:

Whether this vibration is to be called sound, with subjective connotations, or merely shaking, with physical connotations need not confuse us if we keep in mind that vibration is only potentially stimulating for an organism. Whether or not it is effective depends on the receptive equipment of the animal.

Vibration is, for Gibson, an unformed matter that is given shape and organized in different ways. Its sense is dependent upon one's “receptive equipment” that would pick up the information embedded within them, that could transduce or actualize them into distinct messages or sensations—as sound, light, heat, or touch. While they become sensible in those forms, it is not clear whether vibration can be sensed as such. It need not confuse, as Gibson informs, if vibration—as potential—is kept separate from its actualization in sense. Shelley Trower (2012, 3) has likewise described the 18th and 19th centuries scientific and cultural imaginations of vibration as an attunement to a potentiality, to what “lurks” within and beyond: what is inaudibly within the audible, invisibly within the visible, unconsciously within consciousness. Vibration had been used as an index for what threatens the cohesiveness of the self and the body, of the reservoir of forces through which things take shape and sensations are contracted, and of what lies beyond the human and its thresholds of perceptibility.

As unformed potential, vibration has also been figured and granted the power to loosen and unclasp binaries, of nature and culture, body and environment, the sensible and the perceptible, the human and nonhuman, in recent social theory. In Vibrant Matter (2010), Jane Bennett uses “vibration” to describe the ways in which nonhumans have a capacity to act and make a difference. Vibrancy, for her, is the charge of potential forcefields that activities generate, a vitality immanent to assemblages yet irreducible to what is assembled. A force “better imagined through terms such as quivering, evanescence, or an indefinite or nonpurposive suspense” (Bennett 2010, 55). In a similar tone, the vibratory has been granted an ontological (and cosmological) force (Hansen 2015; Boon 2022; Grosz 2008; Goodman 2010), not as a substratum of being that holds steady, but oscillates and quivers. ⁵ As Steve Goodman (2010, 82) writes in his discussion of the ontological force of vibration: “What is prioritized here is the in-between of oscillation… Vibrations always exceed the actual entities that emit them. Vibrating entities are always entities out of phase with themselves.” In resonance with the thought of Gilles Deleuze and Félix Guattari (1987), a world in “becoming” is vibratory. Vibration is conceptualized as both unformed matter and as what exposes the body to what is beyond it: “a vibratory wave that opens up the body to these unrepresented and unknowable forces, the forces of becoming-other” (Grosz 2008, 80). This potentiality of vibration has also been mobilized in discussions of the affective relations constituted through sound and music (Eidsheim 2015): vibrations taken as the impersonal forces of sound that constitute embodied experiences (Trower 2012) or sonic forms of sociality in dancehalls (Henriques 2010).

If STS research complicates these versions of vibrations and their potentialities by empirically situating them within technological, sociomaterial, and historical contingencies and relations, this has been done primarily by transducing and converting vibrations into sounds and noises (Hennion and Levaux 2021; Pinch and Bijsterveld 2004; Thompson 2008): vibrations transduced through the ear, or the technologies modeled on the ear (Cardoso 2019; Helmreich 2008; Hsieh 2021; Sterne 2003). Others, however, have slid down the spectrum of human audibility and beyond, to the lower frequencies or infrasounds to tune into vibrations (Friedner and Helmreich 2012; Peterson 2021; Roosth 2018). Below 20 Hz, vibrations are taken as potentials for rethinking bodily capacities. Michele Friedner and Stefan Helmreich (2012, 81, 77) have shown how vibrations create a shared space of experience for “diversities of sensory socialities;” as a mediator, vibrations “may produce shared experience, but it does not therefore produce identical experience; even within ‘one’ individual, sense ratios and relations may shift and mix synaesthetically.” Sophia Roosth (2018, 110) has likewise found in infrasounds a “more capacious understanding of sound [that] could consequently reorient its focus away from not only anthropocentric but also ‘earcentric’ models of sonic perception in favor of an extracochlear modality that recognizes entire percussing bodies as vibratory sensory apparatuses.” In other words, the vibratory cracks open the body as organized into distinct sensory organs, indexing experiences where the senses work with one another and merge together synesthetically in acts of sensation, but also where the senses may “fail” or where perception becomes confused. Vibrations draw attention to how “the more we concentrate or are concentrated upon one sense, the more likely it is that synaesthetic spillings and minglings may occur” (Connor 2004, 153; Kapchan 2015). From the point of view of vibration, the schema of the body as organized into pre-established sensory organs that contract sensory information from the environment in clear and distinct ways comes undone.

Vibration has thus been used to trouble the idea that there is an essence or schema to a body that precedes engagements with the world, and, as some STS research has described, aligning sensory categories with sensory or bodily experiences requires work and technique, which sometimes do not match up or align (Alaimo 2016; Barad 2012; Latour 2004; Murphy 2000, 2006; Waterton and Yusoff 2017). There are, in consequence, sensory knowledges and experiences that can be (made) illegible or “imperceptible,” but can also open up the body to other sensory potentialities. In what follows, the article tells two stories to describe how the “sense of vibration” pushes against essentializations of the body and the senses, troubling models of sensation that rely on clear and distinct senses, but also highlighting the porosity and contingency of the human sensorium. These stories will outline that while vibration is sensed across modalities (Ballestero 2019), it is also not always clear within which sensory modality this happens. Destabilizing normative views of the body, vibrations can confuse the senses and how they mediate a body's relation to its environment, and further, open up the body to other potential senses, and ways of knowing. The two stories that follow explore what it means to be affected by vibrations.

The Ground Falls and Falls and Falls…

Just a few houses down from where I am staying in the outskirts of Paris, I meet the group behind the posters. Residents who live along the D35 TER road: Pierre, a videographer; Beatrice, an artist; and Samuel, an architect. ⁶ I arrive at the house of Beatrice, and we meet in her studio that faces the road where the unwanted vibrations originate, and where they tell me the story of their protest.

It begins with a sinkhole. In 2016, a 3m-wide and 9m-deep hole had emerged on a nearby street. It had happened after a heavy truck passed. This truck sent pressure waves, vibrations, through the ground, unsettling the largely unknown, mostly filled in, gypsum quarries upon which people lived. These quarries had been there since the 14th century and had last been mined in the late 1800s to supply the gypsum and plaster for the Hausmannian reconstruction of Paris (Arènes and Grégoire 2023; Faytre and Gaucher 2024; IGC 2017, 2022; Le Dantec 2016). The vibrations emitted by the trucks as they rolled along the asphalt disturbed the barely settled soil below, causing ruptures in the surface, as well as cracks in the street, building foundations and within their own homes. This is the current situation, the protesters tell me, pressing their fingers into the table: there is a local road with heavy trucks and their vibrations, which combine with the problem of fragile subsoils, dwellings, and underground cavities.

In 2017, following protests from local residents and resident associations worried about these underground mines that have now, thanks to vibrations, resurfaced, the Inspection Général des Carrières (IGC) had published a report on the status of the quarries (IGC 2017, 2022). And, in 2023, the Direction Régionale et Interdépartmentale de l’Environnement, de l’Aménagement et des Transports d’Île-de-France initiated the process to develop a Plan de Prévention des Risques de Mouvement de Terrains (PPRMT) to assess the risks associated with the quarries. ⁷ The problem, Beatrice and Pierre point out together, is that nobody really knows what is going on underground. The IGC cannot fully know the state of the quarries, which were filled in the late 19th century, but not completely. Instead, they rely on local surveys and extrapolate from the limited available information. Another issue is related to the old, dilapidated water pipe infrastructure underground. This has a multiplier effect because if pipes leak or burst, it further weakens the stability of the ground. As Pierre notes, “on this site there are water leaks, leaks from water pipes that are actually causing the earth to disintegrate, to come apart, and after a while it cracks.” This leaking water destabilizes the soil used to fill the quarries back more than a century ago. But this soil is clay and takes time to settle: “it was put there 100 years ago, or maybe 120 or 130 years ago, but it takes 200 years for it to stabilize. There are parts where there are 20 meters of infill….But it takes a long time to settle, and what's more, this clay soil, it has problems of swelling and shrinkage.” The soil is alive. It breathes. Constantly changing according to patterns of dryness and wetness. It's very problematic, they tell me. It's all mixed up. “And now,” they emphasize, “and now, we’re adding heavy trucks that scream and vibrate. That's the cherry on top!”

The vibrations from the passing trucks, recently redirected to this residential road to alleviate traffic on a nearby road, disturb the subsoil, cause old water pipes to leak, which continues to shift the ground, unsettling the former quarries, which then return to the surface, cracking the asphalt of the road that eventually collapses. “When the sink hole creates a hole like that,” Beatrice explains, “that happens when there is a gallery underground. And if there is a collapse in the gallery, and it happens especially if there are vibrations, then the ground falls and falls and falls and collapses. The hole grows.” Although the cracking ground is the indelible mark left by the trucks’ vibrations, it is the vibrations too that make legible the unknown risks underground (Ballestero 2019). The vibrations make visible the uncertainty of what is underground; the unknowns of a history of extraction brought back above ground through heavy vehicle traffic and urban planning.

Or, at least, that's how they want to frame their argument, as Pierre explains:

we’re dealing with the fragility of the geology and the fragility of the soil. It's an argument that could still help us get rid of these heavy trucks because ultimately there's not much we can do. I have the impression that it would be much more complicated if we didn’t [tell that story]. I have a general impression that people accept it.

In other words, a protest against vibrations as such would be more complicated. If it were a protest based on the sensation of vibrations, the ways in which they kept them up at night, disturbed their bodies and everyday life—that story would be much more difficult to tell.

Following the meeting in Beatrice's atelier, Pierre took me to see his house. He wanted to show me the cracks in the road, in the foundation of his house, and inside his home (Figure 2). He wanted to show me that the vibrations did in fact exist and had effects. These are traces of the vibratory activity invisible both underground and in the air. Inside his home, near the front door, he also showed me a crack that haphazardly leaks downward. Through his reflection in the mirror, he poignantly tells me that it is here, every morning, that he can see the vibrations that he feels within and through his body (Figure 3). However, these are sensory experiences that are difficult to articulate through the existing regulations because they are not legible—seemingly imperceptible—within their parameters. Either vibrations are already transduced into the framework of noise as auditory sensations, or they are associated with what happens underground, only visible in the cracks within their homes.

Figure 2.

Traces of vibrations at the home of Pierre, one of the protesters against vibrations. In these photos taken in July 2023, Pierre points to cracks in the road, on the property fence, and in the façade and exterior wall of his house in Paris; these are signs of the existence of the vibrations (Source: Author).

Figure 3.

A sign of the vibrations inside. This photo was taken inside the front room of Pierre’s home in July 2023. There is a mirror that shakes as trucks pass, and a faint crack has appeared below the mirror.

“As we dug deeper,” Pierre told me, “we realized that the nuisances that we sort of accepted, we realized that there were a lot of strange things; there was a lot of fatigue. And so, the aim [of the protest] is that, well, I think it's the vibrations. It's like noise. It becomes almost unconscious.” Digging deeper into the strata of their everyday lives, there was the accumulation of vibrations that not only posed risks to the stability of the ground, but that accumulated in their bodies. Immanent to the effects of vibrations visible in the cracks in the road and their homes are the effects of vibrations in their everyday lives, their wellbeing, and bodies. “It will be important,” he mentions, “to do a study on the effect of the accumulation of micro-vibrations. That is to say, when a heavy truck passes by, it makes you vibrate. But we’re within a threshold: when 150 of them go by and cause vibrations, what effect do these micro-vibrations have? …It's micro-information. It's micro-stress, too.” Vibrations become unconscious, “micro”—below audibility, invisible, barely felt, perhaps forgotten—outside of what is understood as the standards of human perception, and illegible within the regulatory frameworks based on them. But the effect of vibrations on the body can also be difficult to explain to family members and neighbors who may hear the trucks, but do not feel the vibrations, who do not understand why their partners sleep in the back bedroom, or cannot sleep, or who have unbearable headaches, wincing each time a truck passes.

But what if you did pay attention to them? What if they were no longer forgotten, unconscious, lurking inaudibly within noise? What would it mean to sense vibrations qua vibrations? Pierre, again:

I feel them physically. I feel the walls start to shake and there are little noises, really. It's like an earthquake. A small earthquake. And all of a sudden you feel yourself; you feel that everything around you is moving, the ground, and—so my entire self vibrates, everything vibrates, with micro-noises from all over the house, which is incredibly distressing.

Boundaries begin to blur as everything moves around you. It is unclear where it is coming from; a little bit coming from everywhere. Figure and ground, body and environment merge. You feel the vibrations internally, but also you feel yourself outside of yourself overtaken by them. Your entire self-vibrates with micronoises, not only heard, but felt. What Pierre's description of sensing vibrations draws attention to is the challenge of making sense of vibrations, of giving shape to what is both difficult to locate in the world and in the body as sense. There are three ways this becomes apparent. First, it points to what Despret (2004; see also Shapin 2016) has called the “ambiguity” of having a body, of being both subject and object of the same experience: all of a sudden you feel yourself. Second, you are overcome with invisible forces, “micronoises” that are barely there, inaudibly within the audible, and yet there—they come a little bit from everywhere. Third, sensing vibration for Pierre is sensing something that is simultaneously felt through the body as “micronoises” that can also be heard. Vibrations happen within noises that are nevertheless felt. In the same way that vibrations are physically duplicitous, both airborne and of the ground (Hunaidi 2000), they are also sensorially double, potentially, both felt and heard, indistinct, at once. Tuning into and being affected by vibrations is, perhaps, sensing this duplicity and indistinction of noise and vibration, hearing and bodily feeling, and being unable to separate them.

In her study of noise, Marina Peterson (2021) argues that if sound is treated as touch, it constitutes a “zone of indistinction” (Deleuze and Guattari 1987). Echoing Karen Barad, Peterson (2021, 125) writes that “it is a molecular entanglement, an intermeshing of energy and flesh…There is no object to sound as touch, there is only sensation, proximity, the coming together of differently moving electron fields that do not actually touch but rather repel one another with different levels of force.” Sensing vibration is like touching sound, apprehending what lurks inaudibly within the audible—hearing “micronoises” through the skin of the body. But it is also a coming together of other forces that intermesh with the body, extending bodies beyond their skin (Haraway 1990, 220). Here, along the D35 TER, sensing vibration also suggests an entanglement with histories of extraction and urban planning, of obscure underground cavities, soils that breathe and dilapidated infrastructure, of unconscious perceptions and the imperceptible microstress that builds up with each passing vehicle. This protest, in a way, is a reminder of the confusion of the sensible itself—of how the body is enmeshed with its surroundings, with infrastructures and urban planning—but also of the difficulty of regulating the senses, and organizing them into clear and distinct sensory modalities, of limiting the body to its skin.

Since the late 19th century, the history of psychophysics and neurophysiology, of animal behavior and psychology, has had a fascination with carving out a clear and distinct sense of vibration, of finding it within the sensorium of humans and others. A question had hung suspended in the air, charged with potential, guiding their search: is there a body for vibrations?

The Search for the Sense of Vibration

Imagine, the psychologist John Tait writes in 1936, that you are standing motionless at the edge of a body of water in Italy listening to “charming” music, a symphony—the croaks of frogs. To listen, he cautions, one must remain entirely still. Eventually, a frog “starts to pipe. In another moment a nearer frog commences. Then suddenly, right under one's nose, it may be, an animal hitherto invisible becomes piercingly vocal…As the little creature sits at a distance of a few inches, the water below its chin is thrown into tiny ripples by the vibration of the pharynx” (Tait 1936, 692). In sequence, an entire chorus of frogs is soon revealed. How, he wonders, do the frogs sing in turn? Is it the song “in the air,” or is something happening underwater, out of sight and ear? “Plainly” he explains, “each successive frog, after a certain brief latent period, is tremor-stimulated by its neighbor” (Tait 1936, 693). In his laboratory in Montréal, Tait (1936, 690) describes another symphony of frogs, this time “delabrynthized,” without cochlear and otolithic organs. Unexpectedly, even with their ears removed, they continued to pipe. Above the water, he notes the frogs’ “cheery music,” but below, “one experiences a sensation not unlike that which results from touching the terminals of an electrically active induction coil provided with a vibratory interrupter. The water tremor thus set up has such a smiting, stinging effect that is capable of registering an influence even on the skin receptors of one's fingers.” When you dunk a hydrophone nearby, these tremors are converted into an unbearable underwater noise—the frogs’ vibratory screams. It is through experiences with frogs (and fish, cats, and rattlesnakes) that Tait questioned whether all hearing is cochlear. Frogs without ears responded to tremors and croaked; his fingers underwater responded to the vibrations and stung. There must be, Tait guessed, extra-labyrinthine receptors that undergird this sense of vibration. Somewhere in the skin, there are ear-like receptors that responded to these quakes of water and air, for both frogs and humans. Foreshadowing decades of research, he pointed to the Pacinian corpuscles.

Tait's speculations and experiments were one among many within the latter half of the 19th and the early 20th centuries. Scientists, neurologists, and psychologists were searching for the sense of vibration: to pinpoint the sensory receptors responsible for responding to mechanical disturbances. ⁸ Subtle shifts in the air, and along the skin: flutters, flickers, buzzes, tones, rumbles, tickles, whirrs, beats, and hums. (There is a word for it: “Pallesthesia,” from Greek, meaning the sensation of shaking or quivering.) They searched for this within the other senses, digging into the body, through contrasts and analogies with vision, hearing, touch, and pressure; through self-administered tests of feathers, prods, vibrators, tuning forks, music, pushing, tapping, and prodding the tongue and other body parts, rubbing one's finger along surfaces rough and smooth. They mapped out bodies in search of the zones of intensity for vibration and had speculated that this sense is the missing evolutionary link between the animal and the human, the link between touch—seen as primordial—and hearing—the sense associated with sociality and communication. As psychologist Robert Gault (1927, 331) writes, “Remember that the skin was the original ear…that the most primitive man did not hear with his ears and obtain data through that source, for the mollusk of old, like the mollusk of today, had skin and no ears. He pricked up his skin and felt his environment.” They searched for it by digging into the worlds and bodies of others too: animals, plants, and those deemed “outside” the standard human sensorium.

In their book for the general public, The Senses of Animals and Men, animal psychologists Lorus Milne and Margery Milne (1962) write with enthusiasm about the possibilities of the sense of vibration, which they associate with a “sense of wonder” at what lies beyond within. In their chapter on the “Language of Vibration,” they describe how the milieus of animals vibrate in meaningful ways. Spiders use their webs like “telegraph wires” to transmit images; bees communicate through vibratory dance; the purring of cats; rattlesnakes’ and birds’ sense of incoming tremors, or other animals′ alert to predator and prey. “By observing the capabilities of other members of the animal kingdom,” they write, “we come to realize that a human being has far more capabilities than are utilized. We neglect ever so many of our senses in concentrating on the five most conspicuous ones” (Milne and Milne 1962, 20). ⁹ Others found these possibilities in humans as well. “Deaf” and “mute” individuals were imagined as ideal candidates to enter the world of vibration insofar as they were thought to be seemingly detached from the sonorous (Tkaczyk, Mills and Hui 2020). The acoustician Vern Knudsen (1928; see Peterson 2021, 120), in his study “‘Hearing’ with the sense of Touch” explored whether skin could “hear” vibrations through the sense of touch, that is whether the skin was as sensitive to sounds as the ear. Sounds of varying pitches were played toward the skin of individuals to find the “just noticeable differences” between the different pitches. In his 1927 study, Gault had similarly wondered whether individuals could decipher speech and language through a diaphragm in their palms and fingertips; he had imagined throats and ears grafted onto the skin. Talking to the skin of experimental subjects—mostly, in his words, “deaf-mutes”—Gault (1927, 330) concluded that they had a “feel of words” on their skin: “it is feeling speech and musical sounds through the organs of touch in the skin and through the organs of the sense of vibration; distinguishing the feel of one word from the feel of another and associating meanings with different ‘feels’ exactly as we associate meanings with different sounds.” As animals have a feel for their vibratory worlds, “deaf-mutes,” Gault argued, have a feel for words, for the vibrations that go unheard in speech. The traces of vibrations and its sense had therefore often become visible through the worlds that were considered “other,” beyond the thresholds of human sensibility and the curves of human audibility.

This search for the sense of vibration took shape among an increasing awareness of the vibratory world. It coincided with the advent of railways, automobiles, electricity, radio and wireless technologies, the telephone, rifles, mechanical equipment in factories, and a rapidly urbanizing and industrializing world in Europe and North America. A world that was known to increasingly “shake” (Connor 2008), generating a scientific interest “in detecting and calculating vibrations that might otherwise escape consciousness” (Beer 1996; Enns and Trower 2013; Trower 2012, 3). This scientific interest emerged alongside the study of psychophysics, which sought to quantify the link between matter and mind, or how environmental stimuli enter the body through the senses (Fretwell 2020; Hui 2013; Sterne 2012). Drawing a map of the intensive zones of the human body according to thresholds of “just noticeable differences,” they sought to establish clear and distinct senses, often according to Johannes Müller's classic theory of “specific nerve energies,” which associates each of the five senses to their own specific nerve energy. Vibration, however, had posed a problem: Does it have its own sensory organ? Does it constitute its own sense with its own innervation?

These questions were central to the search for the sense of vibration. The search experienced a small scientific “controversy” between the 1890s and the 1920s over whether the sense of vibration was a “bony feeling,” a subspecies of the pressure sense, or its own distinct sense (Geldard 1940a, 1940b). The controversy begins with studies by French psychologist Max Egger in the 1890s. Through a series of tests with tuning forks (hitting bones), Egger had discovered that vibratory sensations continued long after the sense of touch had disappeared, and argued that the vibratory disturbances had passed through the skeleton, along bones, and within the periosteal tissue (a membrane that covers bones)—he concluded that the sensations of vibration were “bony feelings,” la sensibilité osseuse. Egger's position was more or less accepted for several decades, in large part due to the sole use of the tuning fork as a test instrument: they could only explore parts of the skin that could fit under the base of the tuning fork (where bones were prominent).

The idea of “bony feelings” was first contested in 1915, when the German-Austrian physiologist Max von Frey had begun to explore “the skin point by point” (Geldard 1940a, 252). He argued, after a series of tickles, probes, pokes, and stretches of the skin (his own and others′), that there is indeed no separate sense of vibration: the whirring feelings characteristic of vibrational feelings corresponded with pressure points. In other words, the sense of vibration is a mere subspecies of the sense of pressure (folded within touch). In response to Von Frey's studies, in 1925, the psychologist and phenomenologically inclined David Katz (1989) published Der Aufbau der Tastwelt [The World of Touch]. In this work, Katz partly contested Von Frey's conclusions. Drawing from neurological studies, his own studies with tuning forks, existing accounts of studies on hearing and vibration (as well as the accounts of Helen Keller and a “Herr Sutermeister” who wrote of an enjoyment of music through vibrations) and with animals, insects, and plants, he concluded that there was indeed a separate sense of vibration, independent of the sense of pressure. It had a distinct sensory modality. While the search for the sense of vibration had, on the one hand, been interested in extracting it from the sense of hearing, for Katz (and Von Frey) it was, on the other hand, about its similarities and differences with the sense of touch (qua pressure)—and for Katz, paradoxically, it is the closeness of the sense of vibration with hearing that allowed him to claim that there is a separate sense of vibration. There is a shift along the continuum of sense, from hearing to touch back to hearing, and somewhere, vibration.

In The World of Touch, Katz placed special emphasis on the sense of vibration, or what he called vibration feelings. He was interested in “the extent to which other senses also participate in the fashioning of the world of touch” (Katz 1989, 187) and attributed a vital role to the sense of vibration as distinct from the sense of pressure within touch. To draw this distinction, and to locate a sense of vibration in the world of touch, Katz had, as mentioned above, demonstrated its proximity with hearing. Like hearing, the sense of vibration is a “distal-sense:” you can feel across distances without any contact. Vibrations, like sounds, have a temporal form: sensing vibration is hearing a tone along the skin, a pulsing motion. Unlike pressure, which, like sight, is a “static-passive” sense, vibration sensations, like auditory sensations, are “dynamic-active” and do not leave traces. What is important, moreover, is that vibrations consist of spatiotemporal patterns. With vibrations “we experience an incessant waxing and waning of a perfectly uniform tone…A presently experienced fragment of the tone sinks into the past to the same extent that the new material rises on the other side. Here we experience in the strict sense of the term a process” (Katz 1989, 201–202; his emphasis). He explicitly compares the sense of vibration to William James's (1890) concept of a “stream of consciousness”—sensing vibration involves fleeting impressions that merge in a continuous stream. The sense of vibration is not only continuous in itself but blurs together the sense of touch with that of hearing at the risk of confusing them: “I have established that there almost invariably are accompanying vibration sensations that also have a role in the tactual accomplishment. These vibration sensations are closely related in many respects to acoustical sensations, so that occasionally the two types of sensations may indeed be confused” (Katz 1989, 187). In other words, for Katz, the sense of vibration is not the same as the sense of pressure in touch because it is like hearing in terms of its functions. In this way, Katz decouples the sense from its organ and its specific “nerve energy” that is said to determine it. You can hear vibrations in and as touch. Or, you touch vibrations because your skin hears.

It is this proximity with hearing that Katz used to claim (in a roundabout way) that vibration has a separate sense. This troubles Müller's foundational theory for organizing sensation. While pressure and vibration (within the sense of touch) share the same skin-based receptors, there can be qualitatively different sensations (according to different spatiotemporal patterns of excitation and sensory functions) through the same receptor. Unlike Von Frey, who sought to harness the sense of vibration into the sense of pressure and thus maintain Müller's theory and distinctions between the senses, Katz demonstrated that the same receptor could transmit both vibratory and pressure sensations, simultaneously and independently. The same sensory organ can sense different things at once (Zanchetti 1962). But if this is possible, Katz (1989, 209) wondered, what other senses are possible? For him, this opens a “stage of speculation” regarding sensation: “the great profusion of nervous elements in the skin almost requires that even more senses can be distinguished.” For Katz, the sense of vibration reminds us that there are other potential senses beyond those conventionally organized into clear and distinct sensory organs—that, in other words, we do not yet know what a body can do (Deleuze 1988, 17–18).

In contrast to Von Frey's attempt to return vibration sensations into the schema of a body organized through five senses, Katz's speculation that there are more sensory receptors to be found in the body prefigures the neurophysiological research that began in the 1960s. Research that is based less on an “anatomical” view of the senses, like Von Frey's approach, and which foregrounds the spatiotemporal patterns of sensory excitation along particular receptors instead (Calne and Pallis 1966). In other words, bodies began to be understood as in “tune” with environments through skin-based receptors called biological transducers or mechanoreceptors, either superficially or deep within the skin. These sensory receptors acted as “transducers” that “convert a particular form of energy to which each is attuned into the electrical energy of the nerve impulse” (Löwenstein 1960, 99). With this focus on the senses as transducers (imagined as carbon microphones in the skin), there is another model of the sensory apparatus of bodies. In his article “Biological Transducers,” the biophysicist Werner Löwenstein (1960, 99) likens the body to the apparatuses used for the “automatic control of machines and factories—devices that measure temperature, pressure, rate of flow and so on, and feed their measurements into the artificial nerve-circuits of the control system.” The body is figured as an input–output machine where mechanical stimuli activate the senses and energetic forces are converted into signals and messages (nerve impulses) sent to the brain for processing. These signals were also understood to be coded as information: “Biological sensory systems operate on the same digital principle and use only dots” (Löwenstein 1960, 102). Sense-making shifts from the skin to the brain which decodes nerve messages. Within this transductive and computational model of the sensory body, physiologists and neurologists pinpointed two mechanoreceptors responsible for sensing vibration. The first is the Pacinian corpuscle—as both Tait and Katz had predicted—that is most sensitive to higher frequencies, and the Meissner corpuscle, for the lower frequencies. These corpuscles, in other words, are responsible for the reception of transient mechanical disturbances (vibrations) understood as information in an organism's environment, an understanding still relevant today (Guignard 1971; Hunt 1961; Johnson 2001; Mountcastle et al. 1967; Verrillo 1992). The search seemingly ends there: clear and distinct senses of vibration.

And yet, confusion seems to follow—just displaced from the skin to the brain. In a 2021 study published in Nature Communications on vibrotactile pitch perception through Pacinian corpuscles, neuroscientists studied what happens in the brains of mice when their paws are stimulated with vibrations, and found that

a similar computational principle governs the neural representation (and possibly perception) of pure auditory tones and sinusoidal substrate vibrations, [which] is intriguing given that the two emerge from fundamentally different sensory receptors. Actually, it has been proposed that communication via airborne sounds might have evolved from the more ancient precursor modality based on substrate-borne vibration signaling…and might explain the parallels between frequency representation in auditory and somatosensory systems. (Prsa et al. 2021, 5)

Or, as stated in a report in Nature, “despite the fact that sounds—which travel through the air—and vibrations—which are transmitted through solid matter—are processed by different sensory channels, they are both perceived and encoded similarly in the brain” (n.a. 2019; see Prsa et al. 2019). “Could it be,” one of them wonders invoking the “bony feelings” from the 19th century, “that the particular distribution of vibration-sensitive mechanoreceptors along the bones of the forelimb act as a seismograph to ‘listen’ to vibrations? …This somewhat vestigial, yet highly sensitive modality might also explain how we are able to identify subtle clues linked to upcoming natural disasters, or why construction or traffic causes nuisances even when inaudible” (n.a. 2019, italics added). From the earlier anatomical model of sense to the transductive and computational models, the sense of vibration seems to continue to challenge these models of the sensory body that attempt to regulate and organize sensations into distinct categories of sense.

This detour through the history of the sense of vibration returns us to the protesters outside of Paris. It provides clues as to why they were disturbed by the “inaudible” noises of the traffic, why their description of experiencing vibration relied upon different sensory registers, but also why it is difficult to regulate vibrations in contrast to, or distinct from, noise: they trouble the model of the sensory body as being organized into clear and distinct senses. Despite the ways in which these models of sense attempt to circumscribe and fold vibration back into them, vibration remains a source of confusion.

(Conclusion) Confusion

“The flutter of an insect's wings, a warm breeze, a blunt object, raindrops, and a mother's gentle caress:” studies of vibration sensations tend to begin with lists of fleeting impressions along the skin (Abraira and Ginty 2013, 618). If there is a resonance between the attempt to locate the sense of vibration in these studies, and the protest against vibrations that the article began with, it is that they both seek to make sense of what Pierre called the “microinformation” of vibration that eludes categories of sensation based on distinct sensory organs. In 1765, the philosopher Leibniz (1996, 54) also famously wrote of these as “minute perceptions” through the example of the “roaring noise of the sea.” Hearing the uproar of the sea, for Leibniz, is not just hearing the noise as a whole, as one whole sound, as there are also unconscious, minute perceptions of each individual wave, and of the sounds of each water droplet within each wave, that escape notice, that “lurk” within the audible inaudibly. If conscious perception can be clear and distinct, for Leibniz, the “greatest part [of perception] remains in a state of detached dizziness, undifferentiated, unintegrated” (Deleuze 1993, 131). Leibniz called this confusion. ¹⁰ In The Five Senses: A Philosophy of Mingled Bodies, Michel Serres (2008, 172) too develops a philosophy of sensory knowledge based on confusion. In contrast to analysis and its logical impulse, which seeks to divide and separate experience in clear and distinct ways, confusion “associates, multiplies, pours, ties knots without untying them, neither undoes nor separates, causes the convergence of the unanalyzed.” Confusion, for Serres, is not a sign of error in need of clarification, but arises from the entanglement of the senses, the body, and the world. It is a kind of knowledge that gives place to the confused, to sensory experiences that do not easily fold into clear and distinct forms, categories, and classifications. ¹¹

This article was about two or three confusions about vibration: vibrations can be confused with noise; vibration can confuse the boundaries between the senses (hearing and touch), of bodies, ears, and environments, and the limits of the human sensorium. But this article also highlights the epistemic significance of confusion itself. I began with my confusion upon encountering the protest against vibration, and how, while noise is partly vibratory, vibration is excluded from noise regulations. What distinguishes noise from vibration? Is it because vibration is outside of the curves of human “audibility,” as a sensory experience of sound before sound is audible? But can you separate the auditory from the vibratory? Is there a distinct “sense of vibration”? It is not clear—and that is the challenge. The experiences of the protesters and the history of the search for the sense of vibration are captured by these questions, which turn around how sense is made of a sensory experience that is sometimes unclear and indistinct. In other words, both stories explored how the thresholds of human sensibility (and exposure) are dynamic and contingent, and further that they are not clear and distinct, and can in fact be confused. As “capacious” (Roosth 2018), the sense of vibration troubles the model of the sensory body that environmental regulations rely upon. It shows how sensory experiences do not always match these models. They draw attention to how environmental regulations and standards rely upon what Erin Manning (2020, 248) has called the “deficit model of sensation,” a model that presupposes fixed, clear, and pre-established sensory categories outside of experience, and how this can constitute a “regime of perceptibility” (Murphy 2006) that excludes or renders “impossible” particular bodies (Murphy 2000). The sense of vibration is a reminder that there are other sensations and sensitivities, other ways of relating to the world, a world that escapes habituated categories of knowledge.

STS research has long established that, as objects of knowledge, the senses and bodies are assembled in social, political, and technological configurations (Alaimo 2016; Latour 2004; Murphy 2006; Shapin 2016). This article described how vibrations and their experiences slip out of them. I have shown that knowing and sensing vibration happens in and of confusion. A knowledge not of an object, clearly defined, separate from a subject, but in the words of Vinciane Despret (2004, 125, 127), one that “discloses perplexity,” of “signs that wander, [and] hesitate to fix themselves.” Akin to studies of ignorance or nonknowledge (Anand 2015; Croissant 2014; McGoey 2012), confusion can be a useful idiom for giving legibility to “absences,” but also mixtures or mix-ups, of what is not clear and distinct in experience. Rather than error or mistake, confusion can be a way of noticing what eludes definition, is evasive or indeterminate, without seeking closure or explanation too quickly. Confusion can also provide a means for describing experiences and environmental phenomena that do not neatly collapse into existing sensory or epistemological categories, to allow for a “certain suspension of ontologies and epistemologies, [of] holding them lightly” (Haraway 2016, 88). The notion of confusion acknowledges the “hesitations” (Denis and Pontille 2025; Despret 2021; Stengers 2023) or moments of “not knowing” (De la Cadena 2021) in knowledge practices, including those of STS scholars. In confusion and vibration there remains a potentiality over which one hesitates, when signs wander, and where it is not always unequivocally clear what is happening.