I recorded my voice while watching and listening to stuff to force real reactions out of me. This way i can have real voice clips for stock instead of trying to fake it.
I was doing a narration where i had character voices pre-recorded. When i do that, i simply read through the story and paste the actual voices in afterward, but this still sounded pretty convincing.
I recorded my voice while playing freelance horror games; scp-087-b and slender sanatorium. This was so i could get genuine reactions to use as stock voice clips for future use. Some pretty interesting stuff came out. After the voice says "aren't we having fun?".