I have internal voice sometimes but not others. In some things my cognition is far more verbal, working through something like a monologue or conversation. Other times I may have more of a mental image of something, sometimes more in real space and sometimes completely disconnected from real space. Sometimes it is much more abstract with sensations and emotions with very little in terms of concrete metaphores.

Also I can have racing thoughts without it being language. I also have impacts on those racing thoughts from taking Ritalin (ADHD medication) and it is not just the word thoughts but also the flow of other types of cognition.