July 27, 2011: Despite one well publicized failure, the sonic cannon (or LRAD, for Long Range Acoustic Device) is increasingly popular for security conscious merchant ships travelling in the Indian Ocean (between western India and Africa). This vast area has become the hunting grounds for Somali pirates (using seagoing fishing boats or small cargo ships as mother ships.) The pirate vessels have two or more speed boats in tow, and these are turned loose, with half a dozen of more armed pirates each, when a likely target is spotted. Attacking at dusk or dawn, the speedboats can often get close enough, without being spotted, for the pirates to board.
But most merchant ships in the area now have better security. The ship's navigation radar is set to alert the crew is anything resembling a pirate mother ship shows up. More sailors are posted as lookouts (because the radar cannot detect the small speedboats), and if speedboats are spotted, an increasing number of ships repel boarding attempts using a sonic cannon (LRAD). Even cruise ships have successfully used LRAD to chase off pirates.
In most cases, the pirates simply drop their weapons, cover their ears (which doesn't help) and turn away. In one case, there was minimal damage to a cruise ship (several bullet holes, one passenger cabin damaged by an RPG rocket and one injured crewman). If it's a night attack, or one at dawn, the cruise ship passengers often never know that the pirates where sent away with focused sound. In one case, however, a passenger was up at dawn to take a walk, and spotted two speedboats approaching. Before he could alert the crew, he saw the pirates drop their weapons, with some of them covering their ears, as the speedboats turned away. The passenger later found that his cruise ship was equipped with an LRAD (which looks more like a radar dish on a pole, mounted on the deck somewhere that only the crew has access to.)
LRAD is basically a focused beam of sound. Originally, it was designed to emit a very loud sound. Anyone whose head was touched by this beam, heard a painfully loud sound. Anyone standing next to them heard nothing. But those hit by the beam promptly fled, or fell to the ground in pain. Permanent hearing loss is possible if the beam is kept on a person for several seconds, but given the effect the sound usually has on people (they move, quickly), that is unlikely to happen. LRAD works. And on a speedboat, you have nowhere to run. The LRAD operator targets the guy operating the outboard engine, and anyone else who tries to keep the speedboat headed for the target.
But there has been one exception. Three years ago, the pirates simply took the pain, kept on coming, and got aboard the chemical tanker. The three man security team, sensing that the pirates might behave violently when they got their hands on the people who were operating the sonic cannon, decided to jump overboard. Fortunately, the helicopter from a nearby (but not close enough) warship that the security people had also called, arrived in time to haul the three security men out of the water. The pirates had already moved away with their newly captured tanker. It appears that the LRAD in question may have been operating at the wrong sound setting, because of an operator error, or equipment failure. In any event, there have been no other incidents of the pirates ignoring the sonic pain.
Some U.S. Navy ships also carry it, but not just to repel attacking suicide bombers, or whatever. No, the system was sold to the navy for a much gentler application. LRAD can also broadcast speech for up to 300 meters. The navy planned to use LRAD to warn ships to get out of the way. This was needed in places like the crowded coastal waters of the northern Persian Gulf, which the U.S. Navy patrols. Many small fishing and cargo boats ply these waters, and it's often hard to get the attention of the crews. With LRAD, you just aim it at a member of the crew, and have an interpreter "speak" to the sailor. It was noted that the guy on the receiving end was sometimes terrified, even after he realized it was that large American destroyer that was talking to him. This apparently gave the army guys some ideas, for there are now rumors in Iraq of a devilish American weapon that makes people believe they are hearing voices in their heads.