They can see a person asking a question without turning or craning their necks. Housekeeping After introducing oneself, it is a good idea to mention any practical considerations to ensure everyone understands what is expected and is comfortable with the way the presentation is to proceed. If there are refreshments, ensure everyone has been served and has had a chance to finish up so that their attention will be on you, not the food. Also indicate whether questions and comments are welcome or whether you would prefer that they be held during portions of the presentation. Interaction Interacting with the speaker makes the audience invest energy in the topic of your presentation.
People are much more inclined to support something they've invested in.
We like to invite as much participation as possible, in terms of questions, discussion, and participation. Ask the audience to help you out, and give them a specific task. Show that you appreciate their unique perspective and expertise. Even disagreement, as long as it is open and respectful, is better than no participation at all. Anyone who contends with you is doing you a favor by addressing something that other people in the audience are probably thinking.