As someone with hearing damage (work accident that gave me loud tinnitus and hyperacusis), I think LRAD is pretty inhumane device to use against citizens. It can, and likely will, cause permanent hearing damage; and if you think the worst that can happen with hearing damage is you just hear a little less you're sadly mistaken. Might as well just shine high powered lasers into people's eyes that would disable them too.
Just block your ears and walk/run in the opposite direction until you aren't getting your ears blown. Simple.