The big difference between sound in air and vibration in objects.Noise What do we call noise? How can we tell sound and noise apart?Reverberation Talk about reverberation -beration -beration -berationAbsorption Probably the most needed asset between 4 walls. Solution to many problems but to be used with moderation.Diffusion A necessary complement to absorption.Separation, Insulation or (poorly named) "soundproofing".Keep your noise for yourself!Intelligibility What did you say?