Bob Garfield of NPR's "On the Media" interviewed Michael Erard, author of Um...: Slips, Stumbles, and Verbal Blunders, and What They Mean.
Part of their conversation:
Read, or listen to, the entire interview.
BOB GARFIELD: And is [saying “um” or “uh”] a universal phenomenon? You mentioned English. Does it happen in other languages, and do people say "uh" in, I don't know, France?
Other languages repurpose words that mean something else, so in Mandarin the word for "this” and “that" is the word that you fill pauses with. So if you listen to Mandarin speakers, they'll say nega-neka-nega. Or in Japanese, it's ano, which also means “this” or “that.”
BOB GARFIELD: What about the public's patience for vagaries of spoken language? Is there, in fact, an ebb and flow to the way we all handle other people's speech errors?
MICHAEL ERARD: We typically don't hear most of the “uhs” or the “ums” that other people say. There was one interesting study that was done where people are given a speech to listen to and about half of them, natively, listen to the content, and about half of them, natively, without any instruction, listen to the style.
When the content, for whatever reason, becomes extremely boring, people who listen for content start listening for style, and that's when they start to notice the “uhs” and the “ums.” So when people say to me, how do I reduce the “uhs” and “ums,” I say, that's easy; just be more interesting.
The Page 69 Test: Um...: Slips, Stumbles, and Verbal Blunders, and What They Mean.