Filling in a gap in Frank Sinatra's history, Legacy's 2015 box A Voice on Air collects over 100 radio broadcasts recorded between 1935 and 1955. This is the first collection to chronicle this era -- over 90 of its 100 tracks are previously unreleased -- and it's pulled from a variety of sources, including the Sinatra estate's vaults, the Library of Congress, and the Paley Center for Media, each strand assisting in sterling re-creations of original broadcasts from Frank's bobbysocks days, World War II, and the nascent saloon singer of the '50s. Sinatra wound up singing some of these songs in the studio but not necessarily in these arrangements, a wrinkle that would be tantalizing enough but a good portion of A Voice on Air is devoted to songs he only sang on the air. Some of these are little more than novelties -- the flashiest being "(Li'l Abner) Don't Marry That Gal," a song co-written by cartoonist Al Capp cashing in on his hit strip -- and there is a fair share of duets, with both musicians (Nat King Cole, Slim Gaillard) and cultural figures (Gov. Jimmie Davis comes in to sing his "You Are My Sunshine"). Part of the appeal of this set is how the very fact that it's grounded in specific years accentuates transience: there are jokes that need footnotes, broadcasts from World War II, commercials for cigarettes, and other musty conventions that never quite seep onto Sinatra's studio recordings. Here, they're part of the main text. There might be a fair amount of standards peppered throughout the set but they're unwitting anchors for a set that's proudly not timeless. Instead, it showcases a Sinatra on the rise, a singer relying on his inventive phrasing and incandescent charisma, elements that are undeniable and vital even when heard in these appealing old-fashioned surroundings.