What’s that noise? Control sound through design

Have you ever sat in that restaurant where the volume is ever increasing as the patrons all talk over each other? At the beginning of the evening that restaurant was a quiet place where one could hear the subtle music coming from the speakers, but as the room started to fill with people, the volume got louder and louder until it seemed like they had to yell to be heard. Why does this happen? The short answer is acoustics, and it can be accounted for in the design stage of any room, not just rest