Selflessly I did the research for you and discovered that 80% of us hear "the voice". If not, we may be dyslexic or insane (according to scientific studies).
Let me know what you hear when you think, pray, write or read. I'm interested in the reading part right now, but please share anything relative. Your opinions are important and you matter. Don't sell yourself short and miss out.
I am dyslexic, and I do hear a "voice" when reading. Typically it is the same "voice" I hear when thinking, which I think is an idealized version of my own speaking voice. When I first started attending grade school, in kindergarten, it was discovered that I was dyslexic. Fortunately, I had a great teacher who took the time to work with me, and my dyslexia was never a problem after that. It does surface, however, very occasionally when I am extremely tired, but it is a visual issue with letters appearing in reverse order. I am not sure how it would be expected to affect my inner voice.
When reading dialogue I often hear a different voice. When I know what the person sounds like who spoke the words, I hear their voice. So, if I am reading Trump's latest Twit, I hear his stupid voice. Similarly, if reading dialogue from a fictional character who was played by a specific actor at some point, I will often hear that actor's voice, but not always. It will depend on if I was very familiar with reading the character's dialog before having seen the actor portray them. So, for example, if I am reading a Batman comic, Batman is in my inner voice, since I have been reading them since I was a kid. On the other hand, I have noticed that when I read a comic with Captain Cold in it these days, I hear Wentworth Miller's voice, because he is the actor that portrays Captain Cold on TV. I had certainly been exposed to Captain Cold in comics before he was a character on TV, but he wasn't enough of a recurring character for my inner voice to take over for his dialogue, apparently.
Finally, when reading dialogue from a character described as being of a certain nationality, such as Irish, Russian, etc., I hear the common accent of that nationality. This works with any described accent, really. So, yeah, when I read dialogue that is described as a Texan accent, I hear Sam Elliot, or my father-in-law, who sounds just like Sam Elliot.