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Sonic Continuum

A sonic survey of the oceans is as much an exercise in mapping existing infrastructures that shape humans’ understanding of ocean space, as it is a reading into the technometabolic processes that form our understanding of oceanic materiality. In what follows, I introduce how sonic technologies that operate at sea have developed since the laying of the first transatlantic cables and the electrification of what I call ‘the aquatic sensorium’ and redefined the role of ocean media. In doing so, I reflect on how the ‘metabolism of sound’ shapes our spatial and geomorphological understanding of the ocean as well as monitor its conservation, while setting the foundation for its governance.[1] Finally, I expose the military and extractive rationale behind the investment in sonic technologies, contrasting it with tactical forms of counter-sonicity essential for species conservation.

Ocean media

The instrumentalization of the seabed as terra nullius was first lobbied by the transatlantic cable industry.[2] Its occult grounds became a paradigmatic locus for the projection of a particular techno-scientific gaze, as the ocean geomorphology was depicted as a metamorphosing milieu that triggered mercantilist aspirations. The laying of the first telegraph cable by the SS Great Eastern between 1865 and 1866 marked a crucial turning point in history, paving the way for new forms of technologically mediated oceanic sensing, that turned the ocean into a space for exponential business growth. The ocean soon became an infrastructural space, where nature and culture converged, mediated by new logistical projects and remote sensing technologies. The latter brought about a new cybernetic sensibility that incited novel modes of visualisation and audition, allowing humans to sense across spatial scales.[3]

As technologies, such as echo sounders or remotely operated robots expanded the potential for underwater data collection during the twentieth century, the perceptive limits of the terrestrial human continued to expand. This resulted in a changing definition of underwater sensing, as the performance of distinct human optic and acoustic features adapted to the aquatic milieu. Acoustic technologies soon became pivotal means for oceanographic study: the ocean is a highly transmissive medium where sound travels four to five times faster than in the atmosphere, spreading in a plurality of directions and allowing for quick legibility. Sound frequencies become an extension of the human ear that pings back through the darkened ocean space. They carry a refracted image of its geomorphology that varies according to water temperature, salinity, and pressure at different depths, making sound a great forensic medium.

The militarisation of the spectrum

During the Cold War, the ocean became an auditory network where countless frequencies bounced back; mapping territories, locating vessels, and effectively opening up new communication systems. Shortly after the RMS Titanic sank in 1912, the use of SONAR (Sound Navigation and Ranging) proliferated, rendering the ocean as a sonic space populated by military agents listening in search of acoustic cues that would reveal the location of enemy submarines.[4]  With high training in signal/noise distinction and pattern recognition, sonar users developed a heightened sensibility to recognise the catalogue of frequency spectrum variables of vessel and weather noise, seamount reflection, and were widely employed by the navy for surveillance and detection of enemy submarines.[5]

By sensing the oceanic environment, SONAR mapped out different geologic and infrastructural components of the ocean space, but not without confusing early interpreters of its soundscapes. Biotic elements provided indeterminate, or not fully legible readings, such as those caused by the intensified noise of crackling shrimp troupes which produce a collective decibel level of 220.  A seemingly moving seabed, composed of hundreds of small mesopelagic fish that rise to feed off of plankton at dusk, also confused SONAR readings. The intriguing recurrence of this ‘deep scattering layer’ is another example of an erroneous interpretation of biotic geomorphologies. These sonic interceptions caused the ocean’s biologic and geomorphologic features to merge in layered data entries, leaving the listener oftentimes disoriented between signals, and rendering imperceptible the ocean’s spatiality.

Most forms of ocean literacy deployed by military and techno-scientific agents in the twentieth century emerged via acoustic means for environmental sensing. These amphibian technologies expanded human’s peri-acoustic sensibilities, who, unable to hear underwater, can navigate oceanic data landscapes via sonifications and the transductions.[6] Immersed in the ocean’s expanded auditory system, humans interpreted refracted frequencies on the water column, sensing it on an interscalar level, as if the ocean itself was the perilymph fluid of their own cochlear labyrinths. The ocean became an increasingly expansive sensorium and cybernetic space, where infrastructural networks and technological investments for spatial mapping supported forms of environmental survey. The mastery over new spatial dimensions enhanced by elemental media was crucial for successive military incursions and the development of new forms of environmental sensing.

An Ocean of Sound

Over the years, underwater surveillance programs have shifted their course of action from strict military defence purposes to environmental conservation. The hydrophone arrays of the American SOSUS (Sound Surveillance System) project have recently directed their ears to the changing conditions of our planet. Registering sonic events underwater, today the SOSUS is utilized for hydrothermal vent and whale vocalization studies, as well as the monitorisation of water temperature, underwater eruptions, and climate change.[7]

Further advancements in underwater sound technologies have been directed towards acoustic bathymetric mapping. There has been a noted absence of comprehensive and detailed seabed maps, of which we only have approximately 15% of bathymetric charts, according to NASA numbers. Consequently, there has been an international drive to achieve a full bathymetric mapping of the ocean floor within this decade. To create these maps, current methods necessitate the use of multi-beam echosounders or side-scan sonars. These are seafloor mapping tools that use acoustic reflectivity, emitting conical or fan-shaped pulses down towards the seafloor, usually using higher frequencies ranging from 100 to 500kHz, which record the seafloor texture directly. This enables recognition of sediment type, as well as the identification of geomorphologies, which are indicative of fossil resources such as gas.

The use of sound-based technologies is connected with resource extraction at sea. Hydrocarbon prospection along the continental shelfs threatens marine communities, as the continuous search for oil and gas reserves persists. Even in times of planned decarbonisation and dropping market prices, the pumping echoes of oil drilling remain, with over fifteen hundred offshore oil rigs perforating the earth’s crust every day. Furthermore, the extractive plans for seabed mining throughout the ocean’s basins, that have been in the making since the late 1970s, are becoming more of a reality. This unprecedented industrialisation of the seabed endangers the oceans with the production of new alarming levels of background noise in areas that were previously unexplored. This will severely impact, not only ocean species, but also coastal communities that depend on marine resources for their survival – posing a severe threat to ocean sustainability.[8]

Seismic waves also have a long tradition of being used in seafloor study and the locating of underground resources. Seismographs used to study earthquake events have enabled scientists to read into layers of the planet’s crust and identify its constituent elements. One of these techniques – seismic tomography – is conducted by analysing and comparing seismometer readings from across the world in order to generate tomographic models – three-dimensional images that represent the different densities within the planet’s upper layer. Further fossil resource identification was developed by employing techniques such as seismic reflection. This technology is operable by using air guns that emit six to seven 240 decibel shots per minute – corresponding to an alarming number of approximately 7,000 shots in twenty-four hours, with activities lasting consecutive days.[9]

In order for seismic reflection to compile geologic information that reaches 30km into the Earth’s crust, the sonic discharges released by these surveys strongly impact underwater acoustic communities who depend on echolocation for survival. These include cetaceans, who use forms of sonic emission to locate themselves and their food sources in the aquatic environment. Seismic technology’s intense signal release damages marine animals’ ears, swim bladders and other organs, provoking internal bleeding and, in some cases, leaving them lost and stranded on the beach – since the mobility and behaviour of a particular species can be deeply affected, provoking alarming disruptions in the food chain.[10] 

Counter-sonicity as tactics

The use of sound on seas has been invested in forms of control and securitisation since its inception. However, recent examples in ecological conservation suggest the presence of tactical forms of counter-sonicity, proving that there is yet another generative a shift in the exploration of sonic infrastructures and the ‘technometabolism’ of this media. At the same time, when our sonic baselines are increasingly challenged, in an ocean where the crescendo of background noise is a galloping reality, there are other forms of sonic emission, that contribute to reversing this equation of dispossession.

New technologies supported by seismic wave use are currently under study for safer bathymetric mapping and ocean prospection, among them Ambient Seismic field Noise-correlation Tomography (ASNT). Developed by scientists at Stanford University in 2015, this technique has many advantages over seismic surveys, as it is incomparably less harmful for underwater communities. Using a grid of underwater sensors, embedded in the seafloor, connected to a platform by a cable, this network collects real time data of ambient seismic waves traveling through the Earth’s crust. By using signal-processing interfaces that analyse and compare the seismic data, this platform generates a virtual seismic wave pattern similar to the kind generated by air guns, but without recurring to the emission of harmful blasts, and a fraction of the cost.[11] As the voracious speed of capitalist investments at sea in the era of the Blue Economy lies unparalleled, the proposal advanced by these new technologies might allow ocean prospection to take a less harmful path.

Another example is the partnership between the scientific community and the fishery industry in the Azores archipelago, who collaborate in order to avoid the unecessary bycatch of protected species. Betty Lagbauer at the University of Azores developed a study exploring how ‘sonic metabolism’ interacts with the behaviour of a particular species, drawing out effective methodologies to design tactical counter-sonic tools that support the conservation of particular species. In an interview, Lagbauer told me that she and her team have developed sonic devices called ‘pingers’, which emit low frequencies to prevent the approximation of sharks to fishing nets, thus avoiding unnecessary bycatch. According to Laglbauer, the frequency emitted by these ‘pingers’ is the result of long studies on the motion and electro reception of particular species, whose sensing mechanisms and sensorial organs we still know very little about. With the support of other frequencies, the same technology is being used by fisherman and ships along the Aveiro commercial port in central Portugal – a region which is also visited by cetaceans, now endangered by the enlarging of the port’s infrastructure and the dredging of the riverbanks.

Facing the imminence of the rapid industrialisation of the seabed – one of the largest, most untouched and understudied planetary ecosystems – precautionary anthropogenic impact mitigation measures and innovative counter-sonic tactical forms are ever more needed. A renewed, cross-disciplinary survey of the sonic oceans that looks deeply at other-than-human sensing mechanisms allied with trans-oceanic governmental policies might prove not only useful, but extremely necessary, if we are to keep co-inhabiting our blue planet.