Not Really A Problem
As the other answers and comments have said, this kind of verbal boo-boo is always much more noticeable to the speaker than to the audience. If they actually were to notice, congratulate yourself for having kept them awake and attentive with your lively style and important content.
If the misspeaking is important to the content, merely correct yourself and move on. If not important, ignore it and move on. Do not apologize as that distracts the audience. Intently watch some news anchors or radio jockeys to see how they do just that: correct and move on. Note the keywords: move on.
While not really a problem, if it bothers you so much you can take steps to minimize (but never eliminate!) such misspeaking. Here are some techniques I learned as an instructor.
If you know certain words trip you up, replace them.
If you cannot change them because of content requirements, then practice to over-annunciate them. Practice slowly pronouncing each sound separately. Write the word down, misspelling as needed to create these separate sounds.
For example, turn
extreme into three or four syllables: x - tah - rhee - mah.
Practice that way slowly. Then re-assemble back to natural speech. But mentally maintain that multi-syllabic structure.
This trick also helps with certain words that your touch-typing hands cannot quite master.
Really, breathe. Occasionally take deep breaths. Feel free to take a moment at points in your talk to stop, take a deep breath. Straighten your back, letting your shoulder blades slide down into place. The physical act of breathing changes your physiology and your mind.
Your audience will appreciate these moments. They need time to digest your content, and form their own thoughts.
Plan for these deep pauses as part of the structure of your talk. After heavy meaty pieces of content, or when touching on something controversial or thought-provoking, plan to give the audience a moment.
Also grant yourself a few unplanned pauses. If at any time you start to feel rushed or anxious or don't quite know what to say, stop talking. Take a breath, and let yourself plan the next sentence before speaking. What seems like a long pregnant pause to you the speaker will hardly be a blip on the radar of attention to your audience.
Another way to work in pauses is to occasionally ask a rhetorical question. Emotionally for you it shifts some of the attention and burden onto the audience members, as you are challenging them to engage their minds. Emotionally for your audience members, it is a mild "wake-up call" reminding them to pay attention. Taking a long moment lets them wake-up and think, meanwhile giving you time for a moment to breathe and turn your body as you pan across the audience.
Rushing is a sure sign of a newbie speaker. And rushing tends to trigger misspeaking.
Speaking to Colleagues & Friends, Not Audience
The idea of an "audience", the sight of a stage and of ordered chairs, tends to provoke speaker’s anxiety. Remind yourself that you are talking to individuals, not an "audience".
Before your talk happens, have a few chats with a few people who will be in attendance. Give them an overview. Let them ask you a couple questions about the content. Look for these faces during the talk. Lock onto any face and think of yourself as talking only to that person for a sentence or two.
When you find your words lock-up, just think of talking to a colleague over a casual coffee break. I find that literally imagining the visual imagery of talking comfortably with a colleague can unlock those words.
Practice, Practice, Practice, Ad Nauseum
Practice your talk in your office. Practice your talk in front of your cat. Practice your talk in the mirror. Repeat three times, office, cat, mirror, office, cat, mirror.
Not to memorize a speech, but just go through the content step-by-step repeatedly.
Do a "dress rehearsal", with colleagues. Some teams regularly give a "brown bag talk" where they meet for lunch and someone gives a less formal talk.
Keep repeating until you are sick and tired of the content. Ad nauseam is the goal.
This helps in two ways:
- Emotionally, if you are tired of the content, you’ll find your anxiety level will diminish.
- Intellectually, with repeated practice you will find and lock onto certain phrasing, certain rhythms, and favorite sentence patterns. These will roll off your tongue more naturally. Once you have these “chunks” of language at the ready, your brain has so much less work to do during the presentation. You will feel the load lighten mentally, and misspeaking is much less likely to happen.