The music around Boston this summer will feature some of the most venerable names of rock ‘n’ roll of the ‘60s, ‘70s and ‘80s. But though many are well over 50 years old, don’t always expect them to play their age. Meanwhile their Baby Boomer fans are briskly buying up tickets as they too try to recapture the sounds of their youth. Among the featured acts are 68-year old Roger Waters of Pink Floyd, performing his band’s epic “The Wall’’ album at Fenway Park on July 1, and 62-year-old Bruce Springsteen with his E Street Band, who will play Fenway on Aug. 14 and Gillette Stadium on Aug. 18.