I'm not sure it's working for tone 1. I played back the teacher's recording and it thought it was tone 3. i was able to get 2,3,4 right though, and i think it probably helped my tone2
Haha the bottom of the site says that too:
Unfortunately the system isn't very accurate at the moment, but you will quite likely be able to tell whether you are saying the right tone by looking at your vocal pitch contour and comparing it to that of the teacher.