Per has worked extensively with research (and consulting) in the field of Active Noise Control. Active control means that unwanted low frequency sound is reduced by interference with added sound, created with speakers or shakers. The research involved creating efficient adaptive controllers for multiple input/multiple output and to stydy methods for optimizing the positions of sources and sensors. Per has a PhD in Applied Acoustics, with the thesis Active Noise Control of Enclosed Sound Fields (Chalmers & Blekinge University of Technology). Per was a founding member and part owner of the (now terminated) company Active Control AB.

Per Sjösten participated in the research projects Into Noise and Transmission, conducted by Professor Catharina Dyrssen at Chalmers Architecture. These projects were aimed at sound design and funded by the Swedish Research Council. The goal was to understand sonic rooms in new ways, experience more cultural sentences and nuances, develop advanced sound design, find out how sound can support the creation of more clear or more architectural room sequences and how to develop musical-architectural qualities in the urban room.