Years ago, when the parents of a toddler named Claire Chase couldn’t line up a babysitter, they would drag her along to concerts at the University of California, San Diego. That was where the girl who grew up to win a MacArthur Fellowship for her extraordinary work with the flute first encountered the visionary Pauline Oliveros. Playing accordion, often barefoot, Oliveros struck little Claire as “freer and more unfettered in her skin” than anyone she had ever encountered. In January 2013, seven years after the composer-performer’s death, Chase mounted “Pauline Oliveros at 90” at Carnegie Hall. Intensity 20.15: Grace Chase, which was played on that program, is based on poems by Grace Chase, Claire’s grandmother. It spins its web from sounds of the flute, the human voice, and a passel of small percussion instruments, all funneled into an electronic sound interface of the maverick’s prophetic devising. —Matthew Gurewitsch