Noah Zandan has some great research on 'speaking as a leader.' https://www.quantifiedcommunications.com/resources/
Harvard Business Review: How to Stop Saying “Um,” “Ah,” and “You Know” 2018-Aug-1 by Noah Zandan
Finally, I can’t stress the importance of preparation enough. Nerves are one of the biggest reasons people overuse vocal fillers. The less prepared you are, the more nervous you’ll be, which will likely cause you to speak too quickly, trip over your words, and forget what’s next. So practice. On average, the optimal ratio of preparation to performance is one hour of practice for every minute of presentation, but at the very least, Dr. Trey Guinn, one of our communication experts, recommends speakers get in at least three full runs before stepping in front of an audience.
Used sparingly and effectively, filler words can make you more relatable to your audience, give you time to catch your breath, and emphasize key points. That’s why Google built fillers into the latest version of its AI assistant, Duplex. But when they become crutch words, used out of nervousness or lack of preparation, they hurt your credibility. As you prepare for your next presentation, identify the words you lean on most, and train yourself to avoid them. Then, next time you’re in front of an audience, use silence to gather your thoughts, rather than filling the air with sound.