I went the speech therapy route many years ago and it isn't very difficult to train your voice. I have even written some instructions on the process. As far as apps, a pitch meter is about all you need on a portable device. Most any instrument tuning software should work. If you have a PC, Praat which is document in the top of this area is free and will do a far more extensive examination of your voice.
I needed voice surgery because even with therapy my voice was unable to reach the feminine range. Thus I dusted off my 35 year old knowledge and discovered tools that didn't exist the first time around.
