AA: I'm Avi Arditti with Rosanne Skirble, and this week on WORDMASTER: our guest is writer Michael Erard, author of a new book called "Um..."

MICHAEL ERARD: "People who have studied speech patterns notice that there are really two groups of people: one group that says 'uh' or 'um' more frequently and another group that [restarts] their sentences and they also repeat words more frequently. People who say 'uh' or 'um' are not necessarily uneducated or unprepared or unintelligent, in the same way that people who don't use filler words are necessarily more intelligent or competent."

AA: Michael Erard points out that all languages give speakers a way to indicate some sort of delay.

MICHAEL ERARD: "In many languages it's a word like 'um' or 'uh,' that kind of neutral vowel. In some languages, it's 'eh' -- that's Hebrew. In French, vowels are a little rounded, so it's 'oo.' There are other languages that take a word that actually means something and they repurpose it for the filler word. So in Japanese the thinking word is 'ano,' which means 'this' or 'that.' So you'll hear people say 'ano, ano, ano.' In Spanish, it's 'este' [meaning 'this']. And it's something that people have to learn. Children have to learn it. And adults who are learning a language as a foreign language would be better off learning how to pause and delay and make the thinking sound in that language."

AA: Michael Erard has a master's degree in linguistics and a doctorate in English. He wanted to trace the source of the notion that good speakers don't use 'uhs' or 'ums.' He says he figured it had deep roots because it's so strongly held. So he checked ancient Greek and Roman literature but couldn't find any advice against 'um,' or its ancient equivalent.

MICHAEL ERARD: "I thought, well, maybe it's a particularly American concern, and I went looking in some of the nineteenth century literature about how people could improve their vocabulary, improve their pronunciation, get rid of their regional dialects, and there was no discussion of 'uh' or 'um' either. It doesn't really appear until the early twentieth century, particularly after the advent of radio, but certainly after the phonograph.

"And so what I think had happened was that the phonograph was people's first opportunity to hear their own voices recorded back to them. And that really becomes an issue in the age of radio. And it turned out that one of the important aspects of the radio performance was to remove the 'uhs' and the 'ums' -- I think because it didn't sound right somehow. But there was also the fact that the radio broadcasts were commercial. They were selling things, selling advertising on the radio, and the 'uhs' or the 'ums' would take up valuable time that you could use to sell pet food and mattresses and whatever other sorts of sponsorships."

RS: "What is the takeaway message from the book for students who are learning English as a foreign language?"

MICHAEL ERARD: "Part of it, I think, is to not try to speak the way that English is written, but to speak the way native speakers speak. And one of the ways that native speakers speak is they pause and they think and they indicate to their listeners that they are doing so. And so they say 'uh' or 'um,' they say 'you know' and things like that.

"I think for those students and for their teachers, it also becomes important to understand different situations, that there are formal situations and less formal situations and that each of those comes with a set of rules. Because, while I wouldn't want an 'um' in a State of the Union address or some other formal situation, when I'm in my own home I want to be able to use that word without being judged."

AA: Michael Erard is author of "Um... Slips, Stumbles, and Verbal Blunders, and What They Mean." And that's WORDMASTER for this week. To learn more about American English, go to voanews.com/wordmaster. And our e-mail address is word@voanews.com. With Rosanne Skirble, I'm Avi Arditti.