How does Mr. Hooper's preaching change with the veil and how does Elizabeth respond to it?
Prior to wearing the veil, Hooper had not been particularly effective in delivering his sermons. On the day he puts on the veil, however, he is intense, moving the congregation so much that they feel his words penetrating into their souls. They are uncomfortably mesmerized by his words and can't wait to get outside. Elizabeth isn't frightened of Hooper at first as some of the others are, and she asks him to remove the veil and explain why he put it on in the first place. He refuses twice to remove it and will not explain it to her. Naturally, she is upset that Hooper is willing to give up a life of happiness for the veil, and Hooper dies a lonely man.
In the short story "The Black Veil" the preacher puts on the veil to demonstrate that people carry their sins within and unseen. He decides one day to dawn the veil and does not take it off. When people see him they are curious at first but then begin to experience shame about their own sins. The minister develops a passionate way of teaching or so it seems through his wearing of the veil. His lectures have become powerful enough that each person feels like he is speaking directly to him/her.
Elizabeth, his fiancee is very uncomfortable with the veil. She asks him not to wear it. The veil serves as that which makes other uncomfortable and also makes her uncomfortable. It is to different and seems to distance him from the people while at the same time representing unseen sins.