For the past couple of years sonic weapons called LRADs (Long Range Accoustic Devices) have been increasingly deployed against protestors in the United States (here is footage from Pittsburgh shot in 2009 (warning: remove your earphones!)). A step up from mere marketing tricks that make you suspect that you're going mad, these sonic weapons pump out enough sound pressure to cause permanant hearing damage at a distance of a couple of hundred feet. Earplugs don't work because the sound is loud enough to be conducted into one's inner ears through the bones of the skull. Getting behind hard cover probably won't help much because sound reflects off of solid objects in other directions consonant with the laws of physics.
Last night, a very talented hacker of my aquaintenance named Maradydd went on an OSINT spree and assembled approximately 135 megabytes of data from around the Net pertaining to LRADs, including high-resolution images, technical documentation, and sales information and put all of the information online. Some of the PDFs are password protected (they're encrypted with 128-bit AES and will need to be cracked), some aren't. Unfortunately server this archive is hosted on has a very slow link so I've asked for and been given permission to put up a copy of the documents to take some of the load off of her provider.
You can download my local mirror of the documents from here to help save Maradydd's bandwidth. Please uncompress the archive, go through some of the docs, and post what you find for the education of all and sundry.
If anyone wants me to uncompress the archive and put the individual files up to make it easier let me know in the comments and I'd be happy to do so.