What's that thing in the picture? It's a Long Range Acoustic Device--a megaphone with unprecedented clarity and aim that can shoot compact sound waves across several hundred yards at up to 150 decibels. Designed by American Technology Corp., the LRAD is for fending off insurgents, dispersing crowds, flushing out buildings and telling people "not to come any closer," says Marine Capt. D. J. McSweeney. Thirty-three inches in diameter, the LRAD plays MP3s and prerecorded warnings in several languages and has an adjustable screeching tone. "It's very, very irritating," says American Technology's Carl Gruenler. So irritating that human-rights activists are worried about lasting hearing damage.

In February the Marines signed a $1.1 million contract for the devices; the I Marine Expeditionary Force took them to Fallujah and the Navy's Fifth Fleet has them in the Persian Gulf. (McSweeney didn't know if they'd been used.) Miami, Los Angeles, the Port Authority of New York and New Jersey, and the Department of Homeland Security are considering purchases. With protestors coming to New York and Boston for the conventions, might we see the first domestic use this summer? Gruenler hints: "All I can say is there are cities you would recognize."