Jacob Kirkegaard (Denmark, 1975) is a sound artist who researches the potential musicality of layers of sound in complex environments. His works approach themes such as radioactivity in Chernobyl, the thawing of the Arctic, border walls in global and metaphorical contexts, immersive acoustic explorations in global waste management and processes related to the death of a human being.

‘Testimonium’ is part of ‘(de)composition’, a sound art programme curated by Raquel Castro that emerges as an artistic response to the growing waste crisis, inviting the public to reflect on human existence in a world of consumption and discarding. It explores not just physical waste, but also everything that it symbolises: excessive consumption, social invisibility (the waste itself and those who deal with it are frequently ignored) and the urgent need for a shift in mindsets. The title plays with the tension between composition – which combines and organises elements – and decomposition – which disintegrates and transmutes.

‘Testimonium’ allows us to hear the physical and choreographed essence of everything we throw away. It captures sounds and vibrations from plastics, glass, metals and wastewater with sensors, hydrophones and microphones tuned into the din produced by these materials. The result is a rich and moving portrait of the detritus of modern civilisation – an astonishing testimony of that which is abandoned and, sometimes, recovered.

The project has recorded waste streams and their management systems in countries including Denmark, Latvia, Estonia, Greenland, Greece, South Africa and Kenya, exploring landfills, recycling centres and wastewater.

In Lisbon, the research continues with this work, which listens to the journeys waste takes in the Portuguese capital and the mechanisms that transform it. Inspired by the work of John Cage, ‘Testimonium’ calls for a change of attitude: listening to the environment opens the mind so that we can ‘appreciate’ and act upon aspects that we regarded as merely uncomfortable before.

On 31 January, there will be a conversation between the artist and the curator Raquel Castro, and a performance composed by Jacob Kirkegaard, in collaboration with the Portuguese sound artists Clara Saleiro and Ravenna Escaleira, that extends the sound installation into the performance space.