There are all kinds of theories about what makes a room sound good. One of the leading researchers in the field compares concert hall acoustics to tasting wine: some characteristics are easyily classifiable, but perception and taste are part of the equation, too. Another has suggested that understanding the way sound reflects in a room, not the shape of it, is the critical component to good concert hall design.
But the craziest theory comes from a researcher named Zackery Belanger. He thinks that acoustics is primarily a geometric problem, a theory so radical that he was forced out of his Ph.D. program because his advisor disagreed with it.