Gosh, there are a heck of a lot of jazz singers out there. More than 700 at least, according to Scott Yanow, who takes on the daunting task of cataloguing them all. Jazz singing doesn't lend itself to ready analysis, as do, say, the football strategies that lead to a Super Bowl win. Reason being, before you can say who the greatest jazz singers are you have to define jazz singing—and there's the rub.

Yanow gives a nod to the problem and proceeds to offer a working definition at the get-go: to be a jazz singer, first and foremost one must have an interesting voice and contribute in some way to the professional jazz lexicon. Vocal innovation is the key factor in jazz singing, but not scatting necessarily, and Yanow points to Billie Holiday, Frank Sinatra and Tony Bennett as candidates for inclusion.

Yanow goes on to note, by contrast, that great improvising does not necessarily a great jazz singer make: Chet Baker could be one heck of a scatter but wasn't much of a singer. Still, Baker made the cut. Norah Jones, the jewel in the crown of Blue Note Records, did not. Yanow explains why, and it's all very convincing.

These kinds of conversations run throughout the book and give us the second reason to read it: namely, to see who made it in and why. Yanow is careful in his explanations and generous to his subjects, even as some of his selections still beg the question, why this one and not that one? But this is not an official ranking and Yanow is clear when the opinion is his own.

The Jazz Singers: The Ultimate Guide is divided into six sections: the greats, today's up-and-comers, singing instrumentalists, vocal groups, jazz singers on film, and other books on jazz singers. The introduction is full of interesting background information but could have done without the paragraphs on unskilled singers: how much time on Super Bowl Sunday do we spend complaining about the quarterback who fumbled during our high school's Homecoming game?