The military version he refers to is called the LRAD (Long Range Acoustic Device). They are used both for voice communication and hailing, as well as as a non lethal weapon by broadcasting a series of acoustic tones very loudly at the target (Bad guy) that causes the bad guy to want to get away from the noise.
Most famously, an LRAD has been used by a cruise ship to thwart an attack by pirates.
The Japanese whalers are using them against the crew of the "Sea Shepherd" (anti whaling activist ship). So definition of bad guy is ever-changing, but that's an issue with any weapon. At least they're non-lethal (even if tinnitus is no joke, either).
I have heard that these things have been used as torture instruments in small prison cells, also. I'm not a big fan.