As the speaker you no doubt have experience or knowledge that your audience lacks. If there is one-smart ace in the audience who knows more about the subject than you do then they are probably in a minority of one, so relax. The typical audience will always be on your side. As long as you make it apparent that you are making your best effort and are dealing with them honestly they will forgive any inability to answer the odd question off of the top of your head. Do not be afraid to admit ignorance. This is not a crime. The public speaking environment is one of sharing information. You should make it clear at all times that you are there to learn too. If you dignify them throughout your speech, not knowing the answer to a question proposed from the audience will not seem suspicious or out of place. “That’s a very good question. I don’t think I’ve ever been asked that before. I can’t answer it right now. Can I get back to you? See me after and leave me your contact details.” Such an honest admission is sure to win you the respect of those watching on. Modesty is a refreshingly rare quality, especially for public speakers. Prepare for the speaking occasion well. Think ahead as to what questions are likely to be asked. Prepare to answer them just in case. Don’t be afraid to take with you to the lectern a list of frequently asked questions and the most appropriate answers. Neither should you be reluctant to throw any difficult questions back to the audience for comment. If there was someone there smart enough to stump you with a question you can bet that it is likely there is someone else there who can answer the question for you. This has got me out of more difficult situations than I care to remember. Canvass your audience before the event. Find out what is on their minds. From what angles are they likely to be approaching your topic? Will they be supportive or antagonistic? Your chairperson can be a good source of information here. Excerpt From: Mark Porter. “The Way With Words.” iBooks. This discussion is continued in detail in “The Way With Words”, by Mark Porter.