Noren's Acoustilock, which silences computer noise within a nearly-airtight box, sells itself. The booth guy's main pitch: He stands there, gazing at passerby. He opens the box; a CD is playing white noise louder than any computer whir I've heard. He closes the box; silence. Very impressive. Clearly a high-tech system.
So what's the point of a sign reading "Not just a box with foam!"