Who is the most popular living classical composer? According to Bachtrack, one definite contender is the austere yet luminous Estonian minimalist Arvo Pärt, who turns 90 in September. He’s neck-and-neck with John Williams, who turned 93 in February. But what kind of comparison is this? Williams owes his prominence and his millions to his popcorn-and-Technicolor movie soundtracks, which aren’t exactly symphonies and concerti. For deep immersion in Pärt’s diaphanous sound world in this anniversary year, you won’t do better than attending the 15th edition of the Pärnu Music Festival, which the conductors of the talented Järvi family (dad Neeme, sons Paavo and Kristjan) run like their own summer camp on the Baltic. —Matthew Gurewitsch