Why does the crowd grow silent after the speech

Either to listen or to contemplate. Listen to what the speaker has got to say, to hear and feel the emotions he is trying to convey, to criticize his speech either positively or negatively. Contemplate to the lessons or learnings they have gathered upon listening. They are trying to recall the experiences they had before, connect it to the speech, find meaning with it and apply it in their daily lives. Or they are simply in awe of how the speech got in touch with their feelings.