 At the age of six, Rosen began studying with Eleonore Schoenfeld, professor of cello at the University of Southern California.At age 12, his teacher encouraged him to move on, first intending to study with Gabor Rejto; but, when it was announced that Gregor Piatigorsky was joining USC, Rosen auditioned and was welcomed into his studio and the newly created Institute for Special Musical Studies at the age of 13.Growing up, he also studied chamber music with other renowned teachers who joined Piatigorsky and the institute including Jascha Heifetz and William Primrose.