I think I have experienced this while using marijuana, but I am not sure. It is extremely difficult for me to describe but I will try.
I felt like I was trapped in my own body, and became INTENSELY ... 'introverted' I guess you could say to the point of not being able to hear anything around me, except my own voice when I spoke. And when i spoke, it sounded LOUD in my head, and it also sounded FAKE. Like I had forgotten how to show any emotion, like what was coming from my mouth was either fake/forced, or was being spoken by somebody else. During this phase I become intensely aware of how others see me, very anxious, and even scared.
I don't know if this is depersonalization or not but it is a terrible state of mind to be in.