I had an interesting experience recently. I was at an event where the speaker was talking about avoiding distractions. While she was speaking she was completely distracted by the two women who were having a private conversation instead of paying attention to her. How ironic.
I have two observations. The first is that it is incredibly rude to talk while the speaker is talking. Anything beyond “I never thought of that” or “What did she say?” should wait until after the speaker is done.
Second, when you’re speaking you need to be able to shut out those kinds of distractions. Granted, this particular speaker was talking about reducing the number of distractions in your workspace, but, since she’s a speaker, this was her workspace for that evening. I do a lot of speaking. I know how frustrating it is to feel like people are missing something key you’re saying. But, stopping to single them out (whether by saying something or simply waiting until they sense the silence and tune back in) is disruptive to the entire group. Respect the ones who are listening enough to keep going. I know that’s easier said than done, but it’s the professional way to handle things.