Characters will vary as the content of the scripts change. Actors should be comfortable with a wide range of voices, ages, and accents. 

You must have a professional recording set up and be able to get your audio to ACX standards. No background noise, grainy sounds, pops, etc. 
https://www.acx.com/help/acx-audio-submission-requirements/201456300

Please submit your demo showcasing your range. No more that two minutes long.