Another fun story. I did improv comedy for a few years. One of the warm up games we played was someone would start singing a song, then another person would tag you out and sing a different song. I was bad at this game. But I have a few simple things in my back pocket to "play". Somewhere over the rainbow is one of them. The last person was doing some sort of rap, and what came out from me was a rap version, until the crowd helped correct it. I just have no idea what it sounds like other than trying to memorize if it's a high pitch or a low pitch, etc.
Regarding the inner monologue, I do have one. And it feels similar to my ability to visualize. I can control it, give it emotion per say, (not sound for me), but it isn't as strong as a memory of a dream.