The North Sea is the busiest sea in the world. It is also the loudest. Noise blankets the whole sea. From countless ships, oil rigs, fishing, turbine piling, fish farms, mining… There is not an inch where you cannot hear human activity. This is problematic for marine life, where sound is central. They use it for communication, navigation, foraging and mating. Seas are truly sonic worlds.

Zijlijn / Linea Lateralis explores the underwater soundscape of the North Sea. It investigates the relation between the sounds of marine life, or biophony, and the sound from human activity, anthropophony. Guided by scientists, Stijn Demeulenaere made underwater sound recordings at the southern and northern borders of the North Sea: the waters of Belgium and Norway. Due to abundant man-made sound, the recording of the biophony was very difficult, proving the extent of the problem.

Zijlijn / Linea Lateralis juxtaposes the two sound worlds, letting the audience experience the turbulent relationship between them. Six speakers stand on a line, employing a custom lateral spatialization of the sound. Using a counterpoint between the two, the composition gives spectators a choice to come up close or experience it at a distance, creating a new balance between human and marine life with every new listening position.

The line of speakers is confronted by another: nine seawater samples, one from every recording location, form a line in front of the speakers. The samples are in the center of the sound field, enveloping the audience in an ocean of noise. Three maps complete the installation. One, dating from 1777, shows the North Sea before motorized travel arrived. The other two are noise maps that show the current ambient noise levels in the North Sea. For the exhibition Heard by the Deep, Stijn also includes a noise map of the Adriatic Sea because noise pollution is a global phenomenon.

The title refers to the lateral line of fish, an organ that detects pressure variations in the water connected to their hearing. It evolved from the same proto-organ as our own ears.