You can cause similar symptoms with playing a low frequency tone on a decent standard speaker that the target cannot hear but a common consumer speaker can emit

You can cause similar symptoms with playing a low frequency tone on a decent standard speaker that the target cannot hear but a common consumer speaker can emit. edit: It is speculated that it was actually caused by crickets. Reports on that were kept secret until US parliament send aid packages to those affected... Question is probably now if the crickets were Russian or not.