@RaptorChops, I'd say late teens, early to mid-twenties, perhaps. Definitely not 15, you're too hard on yourself

@Rengar, I'd say anywhere in your 20s, leaning toward the earlier ones (21-23), you sound great!
@Shin it's not too much different, if I didn't know any better I'd say it was just different tone fluctuations (e.g. mood, affect, etc. changing your voice).
@Sentinel, I'd guess around 14-15. And yeah it's natural for us to hear it deeper in our heads because we also pick up on the vibrations via our jaws, so it sounds deeper usually than it does to others. Also, some mics don't pick up bass tones as well as treble ones, so that might have something to do with it, depending on mic quality. You sound good though, way deeper than my voice was pre-T!