...many times I have sat through boring lectures, counting the number of um's. I believe the record is 76 in a 1-hour lecture!

Not even close, my dear. By a good order of magnitude.

The scene: Fall, 1961; Emerson Hall, room 101. The speaker: Willard van Ormand Quine, a person of no mean intellect. The course: Philosophy 140 ("Propositional Logic"). Twenty minutes into the lecture, realizing the unusually high frequency of uh-ing, my roommate and I started taking turns scribing one hundred uh's, gave up in amazement and disbelief and stopped at one thousand, with about five minutes left to go in the lecture.

Actual count. First-hand report. Thirty a minute, and more. They came singly or in salvos of up to four and five. I kid you not.