While you stand before a group delivering your well-prepared talk, can you gauge how well you're going over with your listeners? Let your audience tell you how you're doing, not in so many words but with no words at all. Learn to read what listeners are telling you with their faces and bodies. "Listen" to the wordless messages they are sending.
As you talk you will of course apply all you've learned about public speaking. You already know as much as is practical about your audience to ensure that your language is neither over-simplistic nor over their heads. You are well prepared and practiced. Next, consider adding another "p" to your speaker's toolkit: Perception - that is, your perceptions of your listeners and their expressions, positions and movements.
Many listeners, especially those with little or no speaking experience, have no idea how much an experienced speaker can perceive from the front of the room. Your listeners see mostly just you, but from your position you can see as many faces and bodies as there are people seated before you. You're looking at your audience, moving your gaze over the faces in the room, making fleeting eye contact with everyone but staring at no one. You are talking to them, never past them or over them.
There's an old saying reminding us that the eyes are the windows of the soul. As one instructor, well experienced in speaking on unpopular topics, said: "I watch the eyes. Those who don't want to be there, or don't want to hear, will nail me with an expressionless stare. When combined with tight facial muscles, the riveting stare, usually reserved for non-persons, fairly screams hostility."
Blatant hostility aside, are your listeners all looking directly at you? Do they glance from you to your visuals, if you're using any, and back to you when they should? Interested audience members will be watching you and showing signs of listening, while those who are there unwillingly are more likely to give the appearance of taking notes while actually doing something else. The more you can keep them looking directly at you, the better your chances of having them hanging onto your words.
A couple of frowns here and there might mean nothing, but a generous sprinkling of frowns throughout the group may tell you you're not well understood or that some people don't buy what you're saying. Your response to a field of frowns: Pause where you are and say something along the lines of, "I feel that maybe I'm not being clear, or that some of you have a problem with what I'm saying. What can I clarify or explain?" This will often net you a constructive question or two and give you the chance to get back on track with a number of listeners.
A frown can also indicate boredom, as can obvious visual inattentiveness with listeners looking about the room instead of at you, or peeking at watches or stifling yawns. When boredom seems evident, first make certain you're not exceeding your allotted time. Time is a strange variable in public speaking. For a new, inexperienced speaker a few minutes can be an eternity, but for an experienced, enthusiastic speaker time passes far more swiftly than it does for the audience. Handle boredom by asking a question or two, varying your vocal tone, perhaps speeding up your delivery and physically moving about.
Watch for head movements, especially the slight nodding or shaking of the head by those who are approving or disapproving of your message. Lots of nods, you're on the right track. Excess of negative head shaking, it's again time to alter your approach.
A few signals are often so obvious they're almost funny. Most noticeable is the open-eyed skyward glance, the skeptical "heaven help us" look that communicates volumes, most of it unfavorable. Sending essentially the same message is the conspiratorial glance, the sideways look passing between acquaintances seated together. Many audience members have no idea how much the speaker can perceive from the front of the room, and often their fleeting eye movements clearly identify them as listeners you need to try harder to reach.
Reading my listeners' signals has helped me identify audience volunteers when I need them. I always begin by simply asking for volunteers. Once in a while this works, but usually, I have no such luck. I learned early that with some groups I could ask repeatedly and only waste time and risk the resentment of some listeners. Also, people would start to worry that I'll appoint "volunteers" if none came forth.
So now I ask just once for volunteers and watch the faces of the group. When I ask, most eyes in the room always briefly shift away from me; these people don't want to volunteer and some downright fear being chosen. Only a few audience members typically keep looking my way.
In as light and friendly a manner as possible, I ask: "Most of you seem to know each other - are there any willing talkers in the group? Debaters? Folks who like to argue?" This always elicits a few smiles, but it also causes a number of attendees to look toward a few certain people. In a group of, say, 20 to 25, this usually spotlights two or three people. These are always my best prospects; often I'm safe in asking one of them directly, but just as often one or more will volunteer at this point. This process also has proven reliable for identifying the strongest informal leaders in the group.
Some of the "loudest" nonverbal signals coming from an audience occur when you are - or perhaps should be winding down toward completion. These signals become evident when enough listeners are starting to feel you're belaboring your topic and speaking at too great a length. These signals will be glaringly evident if you were expected to conclude by a certain time but are crowding or surpassing that time. Without looking at the clock you can tell when it's time to vacate the podium.
As we all know, the cardinal sin of public speaking is long-windedness, carrying on beyond the allotted time or belaboring the topic. The effective presentation is concise, using few excess words, wasting no time: Be brief be sincere and be seated. As someone so aptly put it, "If the speaker won't boil it down, the audience must sweat it out."
Signs of "We've had enough!" include yawns, glances at the time, folded arms and the not-too-subtle act of putting away pens, closing notebooks and overall squirming in seats. You can't afford to ignore the "fidget factor" or people will just stand up and leave. The mind can absorb only what the seat can endure.
Learning to read and respond to the simplest of nonverbal signs and signals will always help you deliver a stronger, more effective presentation.