I have been studying ultrasound for a special application. It does not make a good weapon because it dissipates at one over R squared, where R is the distance to the target. To have a powerful enough sound to do any damage you’d have to produce an amazing amount of sound. And, while this is possible with graphene, making the transducer would be extremely difficult and cutting edge tech. Also, as the frequency increases, the range decreases. Most likely, the damage is being done with microwaves, which will essentially cook people’s brain even at a fair distance. The answer is a radiation seeking missile. Not only will it find the source, but turn it into a puff of smoke and debris.
How about subsonic sound? Travels very well.
Could they have done this with a MASER of some sort?