In recent weeks, police departments across the country have used so-called “sound cannons” to control and disperse crowds of protestors. Officially known as Long Range Acoustic Devices, or LRADs, these speakers are essentially sound-based weapons that allow law enforcement to broadcast high-frequency audio at a painful volume and in a precise direction over a long distance.
LRADs can cause headaches, nausea and vertigo — all the way to permanent hearing loss.
The folks at Dave & Gabe, a Brooklyn-based installation studio, recently built and tested a DIY LRAD shield that’s portable enough to carry to a protest. They put together a full guide with instructions and test results, but here are the basics.
You’ll need the following:
- 3″ pine battens or 2x4s
- 5/8″ drywall or 1/2″ plywood or 1/2″ acrylic
- 3/4″ conduit
- Insulation (denim, rockwool or fibreglass)
- A drill + screws (material dependent)
You’ll use the pine battens or 2x4s to build a frame — the instructions recommend 26” wide x 34” tall to balance portability and utility. The model includes centre beams in addition to the outer frame.
Once you have constructed a frame, layer the insulation (cut to the same size on both sides) followed by the drywall or acrylic. You’ll also want to drill a 3/4″ hole in the bottom of the frame to thread the conduit through to serve as a monopod.
D&G’s model, which uses clear acrylic as the outer layer, also has a cutout in the insulation for viewing.
Keep in mind that this isn’t a perfect solution that 100% guarantees protection against LRADs. The D&G instructions note that larger devices mounted up high won’t be blocked by the shield. You should also always carry earplugs and over-ear protection if you’re at risk of encountering acoustic weapons.