How can a great speech fall flat if you don't appeal to your audience?

You need to let your audience know that you really care about what you are talking about. You can do this in a number of ways. If you say something that you can do with your body (walk in to the room) then you need to literally do that - show yourself walking. When you say something funny smile and laugh with yourself. The reason that all of this is so important is because you need to realize that during your speech the audience is going to be watching your every move and they are going to be watching your face. This means that every facial gesture will convey a great deal of information to your audience. This means that you need to use your eyebrows your head, and even your shoulders when appropriate! Hope this helps! ;D