Augustine would not even have been physically isolated from his audience, as a modern preacher would be, who stands in a pulpit above a seated congregation. The congregation of Hippo stood throughout the sermon, while Augustine usually sat back in his cathedra. The first row, therefore, would have met their bishop roughly at eye level, at only some 5 yards' distance.This reminded me that the lecturer, preacher, or teacher of ancient times often sat while his audience stood, which sheds light on the passage in Luke 4:20, which describes Jesus sitting down after reading the scripture: "Rolling up the scroll, he handed it back to the attendant and sat down, and the eyes of all in the synagogue looked intently at him." He was sitting down in the teacher's seat, which would have been elevated (like the bishop's cathedra of Augustine's time, centuries later), while his auditors stood.
I surmise that the same practice lies behind Matthew's description in the Sermon on the Mount: "Seeing the crowds, he went up on the mountain, and when he sat down, his disciples came to him" (Matt. 5:1). We are to imagine Christ sitting on the mount, teaching, while his disciples stand and listen, at a slightly lower elevation.
The practice was ancient. Compare these pictures: the first from the Hammurapi stele of the 2nd millennium BCE (which portrays the seated god Shamash instructing a standing Hammurapi in the ways of justice) and a Greek vase, more than 1500 years later (which portrays a student standing before his teacher, who is consulting a