V2K or Voice to Skull technology is explained by this V2K video on YouTube:



So this technology would require a microwave beam directed at a persons head or more specifically, be able to reach the inner ear. But one should be able to block or shield the microwaves path using a metal surface, maybe tin foil, led metal or something of the like. If the voice is caused by sound, then plugging the ears should stop it. Now to constantly impinge a microwave beam on someones head for 24 hrs a day, I guess they would require a specialized helicopter to follow a person around, but I doubt they would be able to do this in a large city and not be noticed, but who knows these days. Most likely the beam would be, in my opinion, directed at a certain location like a embassy, home or the like to drive a given subject nuts, maybe. Good luck.