I started puberty young, at around 9 years old, and have never had any issues with voice cracking. I noticed around 15 my voice would crack slightly when I tried to yell back at someone in another room, and now it's spread to normal conversation. It will crack midway through a sentence or on certain words. It's not nerves, I've tried drinking more fluids, and speaking louder, but nothing works. I'm not sure what's causing it, or what the solution is.