I found this website - because I have trouble hearing the 2nd and 3rd tones this is going to be really helpful. It is an online game that sounds out pinyin and you have to figure out the tone.

http://pinyinpractice.com/tones.htm

My first score is 50 correct 25 wrong!!! One third of my answers are wrong!

I just had another go and got 50 correct and 16 wrong. Dang those 2nd and 3rds.