Reverb

Sound bounces off walls, ceilings and hard surfaces and reaches the microphone slightly late. A small amount makes a voice feel placed in a real space. Too much makes it distant and hollow, and it is close to impossible to remove cleanly afterwards, though AI dereverb tools have improved on that. Prevention costs less than repair: move the mic closer, put soft material at the first reflection points, avoid standing in the middle of an empty square room. As an effect, reverb is set by decay time and pre-delay. A touch on a music bed is common, and spoken dialogue usually sits better dry.