Okay this thing just got even way creepier:
http://www.cnn.com/2017/10/13/politics/cuba-us-diplomats-acoustic-weapons/index.html
Associated Press released an audio recording of the sound that was heard by one of the diplomats, recorded through his phone. Sure enough, it matches what was described in previous reports.
Obviously since that was recorded by a phone and is being played back through your standard phone/computer hardware, the damaging frequencies are 100% absent.
Either they found a way to blast this at significant distance through windows or walls, which is unlikely and would theorically require very large and unsubtle equipment, either the operatives who installed the (much smaller) apparatus inside the houses/hotels were quick enough to remove it undetected when they knew FBI investigators were coming... fucking spooky either way!
