"Trios" refers to the relationship of two keyboards and the pedals of an organ, as performed by accomplished American composer Carson Cooman as he patiently unfolds Eva-Maria Houben's three minimal compositions exploring the relationships between three melodic lines or three-tone chords, presented on the Organ Probsteikirche St. Ludgerus, in Billerbeck, Germany.

American organist and composer Carson Cooman performs three sontatinas, each in three movements, and the 2014 work "drones", by German contemporary composer Eva Maria Houben, a member of the Wandelweiser group, all slowly evolving works of tone and subtle harmonics.