Funny thing is I read a fascinating story of a girl who thought she was crazy cause she kept hearing voices, but her psychiatrist later found out it was her inner voice. She developed it suddenly during her teenager years, before then her head was a quiet place.I don't know, it's probably a language barrier making me unable to understand what you mean. Cause the things discussed here sounds more like a mental health issue. Inner voice=thinking? Or not?
Now, it sounds normal to me, and most of us that have this cannot imagine how anyone thinks without giving voice to the thought. When I read, when I remember songs, when I write, laying on my bed planning the next day, every waking moment of my life I am thinking something and it takes the form of a conversation with that voice.
For simple things it is my own voice. But songs are sung in the voice of the original singer. Fantasies take the voice of strangers and memories play in a video format, with all the people retaining their original voice.
It was very shocking to learn not everyone functions like this.