I can't see the Sinhala Characters
If your device does not support for Sinhala unicodes, Sinhala characters will not be properly rendered.No voice output?
This application uses Text-to-speech engine. To install voice data,Settings -> Voice Input & Output -> Text-to-Speech settings -> Install Voice Data
or
Settings -> Language & input -> Text-To-Speech ouput -> Google Text-to-speech -> install voice data
How to reduce volume?
Click the menu button in your deviceTap on volume
Now you can adjust media volume in your device.