It is hard to stay focused on what they are saying. Other times, a certain silent pause can emphasize a point the speaker is making. They have time to let it sink into their mind. It appears to be an important point because if it was not, the speaker would have just continued on. I feel that this is a way of something important being asserted inaudibly.
Silence is something that people seek.
I remember once going for a walk in a forest and stopping to rest. I was alone, and the forest was silent. I was in awe. There was no noise. The only thing I could hear was myself breathing.