When the game starts, you see a picture that is stationary in the middle, for example an animal. If you then use your voice or sound is made, the picture will respond with an animation and accompanying sound. Then a new picture will appear.
You can also turn the sensitivity of the microphone higher or lower with the slider on the bottom-right. Slide it to the left and you don't have to speak as loudly.
Furthermore, you can change the theme by tapping the upper-left icon and then selecting one of 5 icons.
And the cross on the upper-right is to close the application.