Cooman is a prolific composer, having composed almost 1,000 works by the time he reached age thirty. As a performer, he tours as a professional organist concentrating on the performance of modern composers; he has premiered more than one hundred works for organ.[3]
Cooman also writes on music, having been editor of the Living Music Journal from 2005 to 2009 and a frequent contributor to the music publication Fanfare.[4] He is currently composer-in-residence at Harvard Memorial Church.[5]
In 2018, Cooman wrote Two Orgelkids Pieces, specially composed for the so-called "Do-organ" of Orgelkids. One of the compositions is dedicated to Lydia Vroegindeweij, who started Orgelkids in 2009.[6]