I do have an inner monologue. Not always on though, many times it's either silent or I just listen to some bits of music in my mind.
Meditation is fantastic to clear the mind. Focus on the breath. Find the space between breathing in and breathing out.
When you mentioned the concept of volume I realized that somehow all is at the same volume, always?, a bit lower than a normal conversation in real world for example.
My inner monologue is loud. I rarely try to quiet it. I do like to come to resolution though. Writing my thoughts or explaining them to others I trust is usually how I handle it.
I sometimes wonder what it is like to not have this inner monologue / thought process. Must be boring.
not only do i have an inner monologue i also have quotes and what not from various songs and movies ive seen. they will pop up every day. sometimes i think im crazy. i dont try to quiet it down, i like to just say it out loud. im def crazy