Once upon a time, orchestras required instruments. Then computers reproduced the sounds of symphonies. Now, band geeks are playing iPhones. Stanford University’s newest ensemble is called MoPhO, short for Mobile Phone Orchestra. MoPhO plays mostly improvisational pieces using an iPhone application. Each player touches a button onscreen to select a tone, then tilts, twists, or shakes the mobile phone to change pitch and timbre. The group also performs chamber music and pop covers using one of his other apps, Ocarina which turns the iPhone into the 12,000-year-old wind instrument.