'Boom!' Says the Lord

What kind of a sonic cannon can strip the forest bare, break cedars and cause mighty oaks to whirl?

As mariners in the Indian Ocean know all too well, the age of piracy is not over. Twenty-first century captains no longer fear the likes of Blackbeard, flintlock pistols tucked into his silken sash. They're more worried about Somali pirates bouncing across the waves in speedboats, racing to overtake slow-moving container ships many times their size.

Pirate assaults these days are all about speed, proximity and brutality. If the pirates can get within range, their automatic weapons and bloodthirsty ways are a match for most lightly armed merchant-marine crews.

For the ship captains, it's all about keeping the pirates far away.

Fortunately, many merchant-marine and cruise ships that ply the Indian Ocean are now equipped with an effective defensive weapon that does just that.

It's called a sonic cannon -- or, in U.S. Navy jargon, an LRAD. The acronym stands for "Long Range Acoustic Device."

The Navy developed LRADs after the disastrous October 12, 2000, terrorist attack on the USS Cole, off...