Post Horn is a free impro electroacoustic duo comprised of Raul Keller (modular synthesisers, sound objects, voice) and Hello Upan (electric violin, sound objects, loopers, voice). Since the early 2000, they have been performing as solo artists and collaborating in various experimental sound projects and together as LokaalRaadio and Project Unison focusing on the performative live aspects of sound and noise. Since 2020 Post Horn is rediscovering electroacoustic (microphones, dictation machines), acoustic (brass percussion, bells) and alternative sound objects (hunting whistles, bird lures) in a dialogue with electronic live-synthesis. The duo still focuses on finding the fragile balance between sound and noise in the dialogue of the two performers.

Improtest is a concert series that brings improvisational music from local and foreign authors to local audience. The concerts have been taking place since 2005 once a month.