If you hear no sound from our game, you might have a muted sound without knowing it. Our game uses the default IOS Audio sound strategy and does not output sounds when the sound is muted. Not all applications do. Some users, experiencing a lack of sound in our game but sound in other apps (like youtube or ipod app) can mis-attribute this scenario as a bug in our program, while their sound is muted.
On IOS, you can mute sound by hardware (the switch on the side of your pad/phone) or software. From IOS 4.3, you can decide what the hardware switch will do: lock screen or mute sound.
When you hardware switch is configured to lock screen, to un-mute the sound, double touch the home button, swipe the bottom bar to right. This gives you the volume, mute, screen brightness, audio player bar. Unmute.
Some (technical) articles: