When you see those audience members that are not quite listening anymore. Stop and start interacting with the group. Ask questions from the audience members. Get them involved in what you are speaking about. This will awaken those that were lost in your speech and bring them into the conversation.
For those times when you can’t get audience members involved; consider having someone out in the audience watch the people and take notes on reactions, interactions and more. Then later look over the notes and make improvements. The next time your delivery will be better attentive.
Leave comment below on what you do to make sure your audience stays in tune to your message?