Acoustics is given a low priority in many building projects. It usually doesn't start off that way at the beginning of the project but its high status can be slowly chipped away by noisy site selection, misprogramming of the building, cost-cutting measures here, nonprofessional opinions there and compromise (pronounced "surrender") by weary building committee members who just want the project to be done.
I have seen changes made to structural, lighting, electrical, mechanical, plumbing, room finishing and hardware cause unacceptable background noise levels, create standing echoes, produce annoying peak resonance and create various other acoustic anomalies. Most of these acoustic problems are built into the building, and cannot be repaired without great expense. Wishful thinking and off-the-cuff remarks often run counter with the laws of physics, and as any Trekker can tell you, "You cannuh change the laws of physics."