What is the true origin of voices when people are speaking in tongues?

This is almost always another consciousness working through the person. It can be a dark spirit or an extraterrestrial, and both phenomena may occur in close conjunction within a particular individual. There are many projects in which both types of beings have a large stake in what happens and will be working side-by-side and will be involved in manipulating a human host and in multiple ways. This capability is particularly valuable in scenarios involving a kind of takeover and will serve the Extraterrestrial Alliance to have high-level compatriots with whom they communicate well, and can reward their superior rank and status accordingly, and this will help foster loyalty, despite the fact there is only a sinister desire for human control and manipulation.