Why does my English Bulldog go nuts when I cough? He barks like crazy at me but not when my wife coughs!?

Your cough must sound like a bark...your voice is (I am uming) deeper than your wife's...:) or, something about the timbre of the sound excites him. My pit bull puppy barks when people shovel...something about the scraping of the shovel on the ground gets her into a tizzy. Who knows what they are thinking...