Jazz critic Giddins's latest subject will probably surprise those who think of Bing Crosby (1903-1977) as ""a square old man who made orange-juice commercials"" and sang ""White Christmas"" every year on TV. Giddins reminds us that, in the 1920s and '30s, Crosby was a very jazzy singer indeed: ""the first white performer to appreciate and assimilate the genius of Louis Armstrong."" This sober, comprehensive biography lacks the thematic breadth and action-packed sentences that made Giddins's Visions of Jazz so memorable, but it's a perceptive portrait of Crosby as a man, a singer, a radio personality and a budding movie star in the loose, creative years before he hardened into a monument. Giddins's account of Crosby's middle-class, Irish-American youth in Washington State astutely stresses this singer's years of Jesuit schooling, which made him unusually well educated for a performer and grounded him in values that contributed to the modesty, reserve and self-confidence American audiences found so appealing. Tracing Crosby's rise through vaudeville, Paul Whiteman's band, short films and radio shows, Giddins also offers a mini-history of technology's impact on popular music, most notably Crosby's famous ability to use a microphone to create a more intimate singing style. There's a bit too much background on minor characters and on forgettable films before readers arrive at The Road to Singapore, which launched Crosby's epochal partnership with Bob Hope. But Giddins amply makes his case that Crosby ""came along when American entertainment was at a crossroads [and] showed it which road to take."" Photos not seen by PW. (Jan.) Forecast: Giddins has long been popular among serious jazz fans, and his name recognition jumped after Visions of Jazz won a National Book Critics Circle Award in 1998. The first volume of a multipart biography, this book will be further boosted by advertising and an eight-city author tour, including an appearance on Ken Burns's PBS documentary, Jazz, airing in January.