An effective public speaker should be able to utilize devices that will be able to capture the attention of the audience. One effective means for them to give you that much needed interest is this: get them to go on stage. Make them participate. When someone is on stage and he or she happens to be a member of the audience, the rest will almost always stay attentive. Why? Because they would like to see what you will be doing to one of them. Also, because they are thinking they could be up there themselves and so to save their precious egos from embarrassment they at least need to know what is going on.
No matter how good or excellent you are as a presenter or as a public speaker, nothing beats the excitement of getting someone to be on stage who really should not be there in the first place. What is going through their minds at that moment when you pull an unsuspecting someone from their complacency is that, “Oh my god, what if the speaker selects me to go up there next? What am I going to do?” Then later, “I need to pay attention to this.” A little bit later as you go through your presentation, the audience will then most probably think, “What point is he/she making?” And then as you take your point across, the audience will then get to think, “Now I get it.” Because you made them pay attention, you have forced them to listen and respond to your statement in the privacy of their minds.
However, there are those extremely shy and very sensitive members of the audience who might withdraw from going through the rest of your presentation if they hear you will be calling on them up on the stage. The objective is to gain an audience and not to lose any of them.
Make it clear prior to your asking someone to come up on stage with you that you are asking for a volunteer and that no one will be forced if they do not want to. Notice that if the majority of your audience are shy, once you finally get someone to be on stage, all of them will almost always heave a sigh of relief that you would actually feel a breeze pass you by, really.
Another way to get the audience to participate as well as pay attention is by giving them due recognition. Try to acknowledge a single member of the audience for a specific achievement or a moment of a good performance, or also acknowledge a group of the audience.