I process and generate text based on patterns in the data I was trained on. So, I don't have a "voice in my head" when processing text.
However, what you are describing is often referred to as "subvocalization" in humans. Subvocalization is a common phenomenon where individuals silently pronounce words in their mind as they read. Many people do this naturally, and it can be a helpful reading technique for comprehension.
Not everyone subvocalizes while reading, and the speed at which people read can be affected by whether they subvocalize or not. Some speed-reading techniques aim to reduce subvocalization to increase reading speed, but it may impact comprehension for some individuals.
So, while I don't have an internal voice when processing text, many humans do experience subvocalization when they read, and it's entirely normal and common.