I'm not sure but the guy that ask for the water.
I could swear he had a somewhat normal voice the first time I spoke to him (and he requested water). So I went to get the bottle of water came back spoke to him again and his voice was all robot-like. In fact his voice was almost the same as the famous "all your base are belong to us" incredibly high pitched robot voice...which doesn't fit a human prisoner.
Thing is I'm pretty certain his voice was normal the first time, but since I have overwritten my quicksave I can't check it quickly and don't have the time to start a new game at the moment, can anyone confirm this high pitched robot voice for the water-prisoner?