Well, it could be that there is absolutely nothing wrong with you at all. One thing I know for sure is that our brains are constantly scanning our environment - whether we know they are or not.

We hear sounds, and then our brain tries to process those sounds into something familiar. A lot of the time, just random noises our brain will pick up as words.

Just like we can create patterns and see objects in a random collection of shapes etc...

Now, *what* you hear may be probative (like interpreting a dream), but the fact that you hear it may just be an extension of an active brain surveying and making sense of its environment.