utrumque is a collaboration between Gerhard Eckel and Ludvig Elblaus taking performance, composition, and research as its articulation. Since 2018, Eckel and Elblaus have been developing systems of inquiry that combine custom signal processing software with a wide gamut of different microphones, speaker, and speaker-like objects, to create room-scale acoustic feedback as an act of curiosity. Their pieces are often durational, temporally smeared, sometimes stretching out for hours. The spatial articulation is irregular, activating the performance space in unexpected ways that allows the audience to explore the musical terrain by wandering and to form their own perspective on the sonic material. Active listening is therefore a very important part of their practice. The work of utrumque is situated and specific to the sites that are involved in the composition, exhibition and performance of their music. Acoustic measurements and digital simulations of room acoustics are often important tools and objects of research, as modelling allows tuning to spaces in digital forms when physical access isn't practical or possible. The result is site-specific feedback music that engages with the concert situation as a shared acoustic landscape.