Why no Incoming Face Time sound on iPad2?

Saturday oct 8, suddenly the incoming audio during a Face Time conversation dissapeared from my iPad. A FT recall (from both sides) did not solve the problem. A call to my iPod, by the same caller, gave normal incoming audio. The caller could very well hear me (iPad and iPod)

I checked loudpeaker settings (volume, mute and loudspeaker/volume symbols on the screen) on my iPad: no result. I did a total reset of the iPad software via iTunes: no result. I removed the new Skype app from the iPad and restarted the iPad: no result.

Does somebody know the cause and solution of the missing of incoming audio on an iPad2?