A newly furnished room is likely to be more sparsely furnished, as clutter has yet to be introduced to the space. This means there will be more hard surfaces from which sound can bounce. This creates a noisier environment. The addition of throws, drapes, cushions, even tapestries will reduce reverberation.
Answer: a newly furnished room causes sounds to be louder because the sound can bounce off of an object in the room. an empty room would have less noise because there are no objects to bounce off.
