Complex sentence: While studying in Vienna, he attended the rehearsals of the Vienna Philharmonic under Herbert von Karajan, Leonard Bernstein and Claudio Abbado and later was a member of the New York Philharmonic Conductors Program.
Split into simpler sentences: While studying in Austria, he attended the rehearsals of the Vienna Philharmonic under Herbert von Karajan, Leonard Bernstein and Claudio Abbado. In America he was a member of the New York Philharmonic Conductors Program.