Hi Vinssen,

The influence room features and furnishings can have on the sound depends on its dimensions and its texture.  For most sonic effects, a furnishing must have a large size relative to the room size to make an audible difference.   A typical chandelier is unlikely to change the sound very much because most frequencies of sound pass through such an open structure and its texture is likely not absorptive of sound. 

For more solid structures, like a crossbeam, column, or a soffit, the effect on sound depends on the frequency.  For low frequencies, the size of most beams is too small to affect frequency response; so, we tend to ignore them when analyzing the bass frequencies.  These structures can, however, change how higher frequencies reflect and travel through a room.  The key to understanding is based on the location of the structure; if it blocks a speaker’s signal or an important reflection from a listener, it’s impact can be audible.  I generally try to keep such structures clear of any important sound paths.  A crossbeam is in a good position since it is up high and away from important sound paths.  It’s is unlikely to create a sonic problem.

Room furnishings that can change the sound include columns placed on the side wall and half-walls placed in the room.  I design my theaters to avoid placing such items in the path of important sound signals and minimize their size if possible.