I wrote to the support link (on the
About page) and asked if this was a known bug on the iPAD3...
Here's what our tech support friend Zdenek wrote in reply:
"I have done some searching a while ago and it seems that Machinarium isn't the only app with this problem. So based on that:
1. It could be a compatibility issue with the rolling mute feature - to correct this - set the mute lock to “Muted”, then start the app, and then “Unmute”.
Or AFTER toggling the mute lock, reset your iPad’s setting to factory defaults. Tap Settings > General > Reset > Reset All Settings
2. In some cases the system sound slider disappears completely: Connect\Reconnect via cable."
Give those suggestions a try and please be so kind as to write back with your results.