And the '00s? It's produced some memorably sardonic screeds (Green Day's "American Idiot"), patriotic hell-yeah's out of Nashville like Toby Keith's "Courtesy of the Red, White & Blue (The Angry American)," and dirges of quiet desperation emanating from "The Suburbs," courtesy of Arcade Fire.

But much of the music that has topped the Billboard charts in the new millennium -- Britney, Lil Wayne, Lady Gaga -- might suggest that America has been one big party since 2001, despite the Sept. 11 terrorist attacks, two major wars, a wobbly economy and a bitterly divided government. Likewise, the recent popular manifestations of that unrest, the tea party and Occupy Wall Street movements, so far seem to have been largely lost on popular music.

That has left some artists, music industry professionals and listeners pondering how well today's music is serving the restless masses and capturing the essence of times that indeed are a-changin'.