It's not a theory, even in the sense you mean. It's been going on ever since man existed, it's why we had and still have exorcisms, people aren't being possessed by demons, chemical imbalances in brain causes them to see and hear things that aren't happening and other believers in demons think it's possession and torture the mentally ill for something they have no control over. It also happens in people most other would consider "normal." Like religions believers who think god is talking to them, secret answer, no it's not god, it's just voices in your head! People who see Jesus face in toast and other consumables, it's just a pattern our brain puts a name to because the human brain is designed to detect patterns visually and aurally, and we often detect patters that aren't actually there.
So we hear some fuzzy sounds and our head attributes words to them because the sound sort of matches words we already know, and once we attribute that patterns its hard to get rid of it even when it doesn't actually exist. When you tell people there are words there it also triggers them to try and hear the same words whether or not they are actually there, so the brain fills it in.
If you want to test it properly you need to hand your sound file to someone who has no interest in the game and has not been keyed in to the words you claim to hear and see if they hear the same words. Preferably a few people, with a trial group, you know, a proper blind test.