Piper Ears
Sound Problem on iPad

The iPad has a selective mute feature. When activated it allows some sounds to play through the speaker, and other sounds to be muted.
If the sound in Piper Ears does not play through the speakers on your iPad:

1. Double click the home button on your iPad
2. In the icon area that appears at the bottom, swipe left to right to bring up the sound icons
3. If the icon on the left is a speaker with a slash through it, tap that icon. It should change to a speaker without a slash, and a message should appear briefly that says "Mute off"
4. If the icon on the left is a circular arrow, find the side switch on the side of your iPad, next to the volume control, and change the position of the switch

That will enable the sound for the app.
The reason you have to choose step 3 or 4 is that there is a setting in the iPad (Settings -> General -> Use Side Switch to) that can be set so the switch locks rotation or to activate the selective mute. Whatever is not controlled by the side switch is controlled in the sound icons panel.