Coachella awaits the next artful spectacle of sight, sound

Critic's Notebook: Now that the festival buzz is as much about the visual (think Daft Punk's pyramid) as the aural, artists like Trent Reznor are upping the 'wow' factor.The recent history of the outdoor concert, from a performance perspective, begins with a pyramid. Two Frenchmen known as Daft Punk constructed a massive video-and-computer-enhanced object that blew minds at Coachella 2006 with its gradually unfolding light-and-image show.