I have “encountered” what you are describing.
It goes like this. I’m in a house or on a bus or in a restaurant, and what I’m thinking on is commented about by someone else.
It’s almost like there is a quantum entanglement (THERE ISN’T THOUGH) which feeds the information that I’m having into them.
Upon closure examination though such as recording them speaking or interacting with them based on what I assumed I heard this never pans out. NEVER.
What is obviously happening is that the sound waves hit my ear drums, are then processed, but when they are processed, they are being mixed with my memory and lingual faculties’ information. At the end of the line what I’m hearing has been diluted by other faculties of mine, so that it sounds like they are saying what they are not saying.
This has never happened not once with people I am close to in vicinity, so that I could hear them clearly. This has only happened when there is some kind barrier or distance between myself and them which means that the sound is not clear enough to understand, and I’m only believing I can understand them.
I suggest buying a cheap microphone like a lavaliere the ones they use on talk shows and news shows, and get the battery pack kind. You can search Amazon or online spy gadget stores. Then hide it in your clothes. The winter is perfect because you have to wear more layers of clothes.
Then transfer the data onto your computer, and listen in headphones closely. Compare what you thought you heard with what it actually says.
One thing to remember is that you get used to it until you forget you are wearing it. If you are aware of wearing it because you haven’t been doing it for very long, then that awareness may effect how your faculties process the sounds you hear.