No contemporary pop songwriter has a more direct line to the Great American Songbook than Stephin Merritt, founder and frontman of the indie pop group Magnetic Fields. He serves as the group’s primary songwriter, producer, and vocalist, as well as frequent multi-instrumentalist. 50 Song Memoir, his latest project commissioned by the Brooklyn Academy of Music, finds Merritt revisiting each year of his half century on Earth in song. The five-LP recording covers Merritt’s life story in chronological order, addressing everything from his trials and tribulations of childhood, to romantic travails as a twenty-something, to heartfelt reflections on turning fifty. At Big Ears, Merritt’s performance with The Magnetic Fields will be divided into two evenings of twenty-five songs each. Sure to be a highlight of the festival.