Long Range Acoustic Device (LRAD)

[pnoneal...]

http://en.wikipedia.org/wiki/Long_Range_Acoustic_Device

I would like to know about how this device operates from the engineering folks out there. I just don't have the knowledge to understand how it works. I'm used to using an Amp to power my speakers. IIRC, it takes a doubling of power to increase sound by 3db. Being exponential in nature, it would take tons of power to get to these levels they are talking about (above 130db) for distances the distances they say which can go up to 300 meters for the short bursts.

Can someone educate me on this and offer opinions and what effects this could have on the speakers of the future?

[Sydney]

Basically a phased array of lots of transducers to produce a directional ( +/- 15 degrees ) very-high ( 162db ) SPL pattern
http://science.howstuffworks.com/lrad3.htm

[pnoneal...]

Thanks for the links. I now have a basic understanding of how it works.

[Taterworks]

At InDIYana, we had Paul DeMond on hand from Ultra Electronics, whose Audio Products division located nearby in Fort Wayne manufactures a similar long-range acoustic hailing device called the "HyperSpike". In the HyperSpike device, multiple compression drivers are loaded to short horns around the rim of the device aimed toward the central axis, and they fire onto a cone reflector with a curved profile so that the output incident onto the reflector from any direction is aligned with the axis of the device after being reflected, essentially creating an isophase wavefront that is highly directional.

Point source loudspeakers have a fairly wide dispersion by virtue of their operation as a theoretical point source. Line source loudspeakers have a dispersion pattern that is narrowed in one dimension due to self-interference. A very highly directional acoustic source could also be created by having a group of small radiators arranged in a ring, or a ring-shaped diffraction slot preceded by a horn, creating a large 'ring radiator' or "ring source loudspeaker". This sort of an acoustic radiator would have applications in long-range acoustic hailing, crowd control, and long-distance outdoor signaling such as weather warning sirens.