Schizophrenia

[somethingelseishere]

In the U.S., the voices are harsh and threatening

Right off I think of how poisoned American culture/society is and has been
for so long. Also, one can't rule out various malevolent forms of tech that
could be contributing to it - like voice-to-skull. Not to mention the electromagnetic
swamp of hindrance we've been swimming in since the 70's. 

Could very well be targeted action. Experimentation. 
I'm not opposed to it being more "organic" and just happening
that way - but we've got a pretty strange world going on here
in the US. Even things falling under the header of "organic" will
have fairly wide margins for the unaccountable.