@Hyolobrika @mitchconner @steeznson from what I can tell from both my own experience and external sources, our internal monologue isn't actually speech as we know it. It's a chain of thoughts loosely associated with language concepts and if we think on them with the language part of our brain they retroactively get translated into words, but the brain doesn't waste processing power on thinking with exact words all the time. Hence it's easier to have an internal monologue than to speak out loud.

We can also explicitly have an internal monologue coerced into words, but it's more like manual breathing.

I noticed that the most when I learned English enough for my brain to switch to thinking in it for the first time, when I was abroad and had to use it pretty much exclusively for a whole day. Since a language is also a way of thinking, I sometimes catch myself at chaining a Polish-like monologue with English-like monologue without realising it until I try to think back on it more explicitly and realise it doesn't fluently translate into either.