This information comes from "Sound Reproduction" The Acoustics and Psychoacoustics of Loudspeakers and Rooms written by a pioneer in acoustics Floyd Toole
first reflections
While the consensus is that there should be some absorption in a room, there are two schools of thought on whether one should try to absorb first reflections:
1) Don't treat first reflections: See Toole, Sound Reproduction for info that you don't need to treat first reflections. Toole's chapters 6 and 7 and in many places throughout the whole book, explain that when tested and asked in controlled experiments, people prefer early reflections for music and early reflections help speech intelligibilty. having the first reflections give the benefit of a sense of envelopment and broader spatial imaging (and low IACC) that listeners in Toole's experiments prefer from first lateral reflections.
Of course, you do still want absorption in the room primarily to avoid flutter echoes. But so long as reflections are not so delayed that they start to resemble echoes, people prefer them.
2) The old conventional wisdom, but on the wane (especially among those who have read Toole's book), is that you should treat first reflections.
Possible good reasons to absorb first reflections are:
speakers with poor off-axis repsonse may benefit from first reflection absorption. That is, if your front speakers send out the equivalent of acoustic flatulence to the side to be reflected off the walls, then you probably don't want that acoustic flatulence to be bounced back to you, so you might as well absorb it.
if you are a sound engineer and want to hear only the direct sound, including the direct sound from the surround speakers and don't want to be distracted by the ambiance and envelopment created by the reflections, then you should absorb them.
Apart from those good reasons to absorb first reflections, some people maintain that absorbing first reflections helps imaging. This is inconsistent with Toole's experiments, however.
