It's hard to beat a bird book that offers you an opportunity not only to see what they look like but to actually hear the bird calls and songs. Bird Songs From Around the World does just that, but it might not be your best option.
With bird descriptions by Les Beletsky and beautiful illustrations by Mike Langman, the book features the songs of 200 birds from around the world. Contained in a digital audio player attached to the book, the songs were obtained from the Macaulay Library at the Cornell Lab of Ornithology.
Each bird in the book has an audio entry, and you can pick and choose which you want to listen to with the keypad on the player.
That said, the size of the book, 11 inches by 11 inches, makes it a bit cumbersome to take out into the field. However, a greater problem I discovered is that the section on "North American" birds would be better labeled "Central American" birds.
The author does point out that North America "for our purposes here, includes Canada, the United States, Mexico, and the West Indies." Still, I counted just three species that one might spot in North America, and one of those, the Ivory-billed Woodpecker, is largely thought to be extinct, albeit sightings recorded in late 2004 and early 2005 have now put that "extinction" in question.
I had hoped the book would feature dozens of birds that might be spotted in our national parks. Instead, I found just two: the Roseate Spoonbill, the Magnificent Frigatebird, although if you are lucky enough to spot an Ivory-billed Woodpecker you'd be up to three.
A better book, in terms of learning more about the songs and calls of birds you might see in America's national parks, probably would be Bird Songs: 250 North American Birds in Song, also by Mr. Beletsky. However, I haven't thumbed through that book and so can't vouch for its contents.
A better option for birders would be Handheld Birds, a PDA field guide that not only contains information on 867 North American bird species but also lets you listen to their songs and calls (also, courtesy of Cornell) and allows you to track your own bird list and study range maps.