In the past weeks, Sonic Acts welcomed BJ Nilsen to the Rotterdam-based Spatial Sound Studio, as part of a programme supporting artists working with multichannel sound. A renowned sound artist and composer, Nilsen’s approach to creating music from field recording points towards his research in active listening. His extensive discography spans over 30 years, with releases such as Irreal (2021) on Editions Mego and, recently, True than Nature (2025) on Ideologic Organ. Next to his solo work, he has also extensively collaborated with artists such as Chris Watson, Jóhann Jóhannsson, and Femke Herregraven.

During Nilsen’s residency, he continued his new approach to listening and sound-making from field recordings, and worked on conceptualising the idea of vertical architectural and natural structures as resonant instruments of listening.

Unlike horizontal spaces, vertical structures such as bell towers, cliffs, stairwells, forest canopies, communication towers and lighthouses exhibit distinct acoustic behaviours. One of the most compelling sites to study vertical acoustics in the Netherlands is the historic water tower at Radio Kootwijk – a small hamlet located in the Veluwe, a vast natural park in the Netherlands.

Radio Kootwijk is best known for its monumental radio transmitter complex, built in 1918 to facilitate long-distance communication between the Netherlands and what was then the Dutch East Indies. Although the station was decommissioned in 1998, the site remains architecturally and historically significant. For this project, Nilsen focused on the water tower, constructed in 1922. Originally used to supply cooling water for the radio equipment and to serve the nearby village, the tower now stands as a unique acoustic space within a landscape shaped by both nature and early 20th-century technology.

Using a custom-made microphone array, Nilsen recorded sounds at multiple elevations and then replayed them to capture each site’s unique acoustics. Collecting sound at various heights reveals how acoustic phenomena unfold, offering a three-dimensional perspective on the sonic environment – an aspect rarely explored in conventional field recording practices.

A second visit took place at Het Lage Noorden in Marrum, Friesland – a remote cultural site in the northern Netherlands. There, Nilsen conducted similar research in a former feed silo (voedersilo), now repurposed as an observation tower. Like the water tower at Radio Kootwijk, this structure provides a tall, narrow interior with strong vertical acoustics. The silo’s height and reflective surfaces produce a comparable spatial and sonic response.