The Bee Gees Message Board

Is there a voice synthesizer being used in the song "I Can't See Nobody" or is the singer (also, who is the singer?) actually singing like that? The sound I mean is most prominent in the line "I used to smile and say hello" where it sounds like he's choking on his tongue. Can anybody tell me how this effect was produced?

The singer is Robin Gibb and it's his own beautiful voice