http://itunes.apple.com/WebObjects/MZSt ... 60401&mt=8
The pronunciation and voice is provided by a young women who grew up in Beijing and is the niece of a language professor at the University of Beijing.
Contains a quiz to help test your understanding of the tones in listening as well as understanding.
Provides examples of simplified chinese characters for all accepted tones to help in learning and understanding.
If you have any questions or comments, feel free to post them here.