This is an interesting theory. Probably one of the more plausible ones. I imagine some sort of biological or toxicological attack could cause some sound processing related symptoms.

On the wild end of things one could imagine it being a combination of sonic and chemical attack where the an innocuous chemical structure became active as a result of high frequency sound.

It may not actually have anything to do with sound. The recordings offered as "proof" (of what, we can only guess) have all been explained as normal innocuous sounds.