What emotions does Mr. Hooper evoke in his congregation that he never did?& what do you attribute mr. hooper's new found ability to affect listeners?

By donning the veil, Mr. Hooper of "The Minister's Black Veil" creates an ambiguity that thereby leads to interpretation of motive by each member of the congregation. 

Each member of the congregation, the most innocent girl, and the man of hardened brest, felt as if the preacher had crept upon them, behind his awful veil, and discovered their hoarded iniquity of deed or thought.  Many spread their clasped hands on their bosoms....An unsought pathos came hand in hand with awe.

 This interpretation of the minister's motives for wearing the black crepe separates him from his congregation since each person's heart holds different secrets.  To some, the minister wishes to hide his face because he himself has committed a transgression.  To others, discomfiture comes as they wonder if the minister can see inside their hearts and wishes to bar himself from their sins.

At any rate, the wearing of the veil by Mr. Hooper makes his congregation more uncomfortable than ever before. 

At the close of the services, the people hurried out with indecorous confusion, eager to communicate their pent-up amazement, and conscious of lighter spirits, the moment they lost sight of the black veil.