Work on keeping your gaze relaxed, but steadily in the direction of the person you want to give an answer. If someone else shouts out, simply behave as if you don’t hear them. Don’t turn and look at them, even to say’shhh’ or something similar.
Just let the other responses wash over you and have no effect. If the person you want to speak takes takes a while to from their response, don’t look stressed or over – anxious about this delay.