WAB
Contributor
Have you ever “heard” yourself talk in your head? If you have, then you’ve experienced a common phenomenon called an internal monologue.
Also referred to as “internal dialogue,” “the voice inside your head,” or an “inner voice,” your internal monologue is the result of certain brain mechanisms that cause you to “hear” yourself talk in your head without actually speaking and forming sounds...
From here:

Internal Monologue: What It Is, What It Means, and More
An internal monologue is an inner voice where you "hear" yourself talk in your head. But not everyone experiences this. Learn what it means and more.

I am frankly surprised when I hear that there are people who do not experience this 'internal monologue'. I can't imagine what it would be like not to. According to a few sources, from between 30 to 50 percent of people DO experience this. At first I thought NOT experiencing or hearing an inner voice was very uncommon. My gast is a bit flabbered.
When I read a book I often choose to hear a particular accent, or a specific person's voice. For Shakespeare I like to hear Anthony Hopkins or Ian McKellan, for example. Usually I hear my own voice. If I read an email from my mother, I hear her voice, etc. Of course I know I am not literally hearing a voice...
Any thoughts?