I mean really seen - as in seen through. Actually, you have little choice, you're going to be seen through anyway. An audience can't read your thoughts, but they effortlessly read your inner feeling state, your motivations, your attitudes, the way you see yourself and your life. How? By what you do with your body and voice.
The trick - the most impressive trick - is to get comfortable about being seen through. Yes, that means choosing to be comfortable about who you are.
Intimacy. It's the often ignored part of speaking. Which is remarkable, because it directly effects the impact of your message. Want your message to sink in? Then...
Speak to your audience as if you're speaking with a single person you like and respect.
Then they will feel connected with you. That's partly about your choice of words, but mostly it's about your tone, eye contact and body language. Of course the more people in front of you, the more you'll need to speak up, but think of them as a single person further away from you and shifting about in the room.
Literally, I'm talking about the first words that come from your mouth. The greeting. Many presenters greet the audience with a stiff tone, expression and body language. The words say Good morning, but the message the audience gets is, I'm not talking to people, I'm talking to an audience... I hope it likes me. That kills intimacy and with it much of the impact of your message.
Don't mistake me, this isn't about being friendly. You often will be and should be friendly with your audience, but intimacy, real connection, should be there even in the most serious situations when friendliness would be out of place.
Just before you go out in front of them, imagine that you're about to have a chat with just one person - someone you like and respect. How would you greet that person? What would your expression be like? The look in your eye? Perhaps you would you feel a little warmth and relaxed pleasure in their company. Rehearse that opening greeting and first sentence. Act it out. The research is overwhelmingly on side with the philosopher William James who said, "If you want a quality, act as if you already have it." The quality you want is the ability to connect with any audience.
Want to see someone get intimate from the first words? Take a look at Ken Richardson's speech on education. It's not just his words, "Good morning... how are you?" - take in his tone and expression. Notice how he makes you want to keep watching.
Resolve to start like that yourself.
Have fun. Enjoy your audience.