The short answer: a bad idea.
The longer answer: a technique used several decades ago before it was realized that the disadvantages far outweighed the advantages. Tom Hidley's "Westlake rooms" were the classic examples, but many other rooms used the technique as well. The hard, reflective ceiling has a reverse peak where the low point is in the center of the room and the high points are in front, above the speakers, and in back, behind the listening position.
The reflected energy from the speakers was supposed to increase efficiency and improve the bass response, but as it turned out, it primarily served to create nasty comb filtering effects, adversely affecting imaging and creating an uneven wideband frequency response.
An example: http://www.mediaandmarketing.com/Art...e_Studio_A.jpg