I have noticed that some people pronounce the prefix "un" as if it were "on." An advertisement on the radio will inform me that I can buy the Super-Matic Chomatron 3000 at onbelievable savings, and for this week only I can also purchase the extended warranty to obtain onsurpassed service after the sale. I have never heard "on" for "un" spoken by a local in Michigan or Ohio, and am wondering from what areas of the country I can surmise such a speaker comes.

It wouldn't sound awkward in Newfoundland, but I doubt if that's where your commercial voice comes from. They do all the vowels a bit different here. A Newfoundlander saying that would also stretch out the word.

I've heard that pronunciation from a fellow from the outskirts of Chicago. FTR, the Old English was on- and the on'ry in John Jacob Niles's lovely falsetto rendition of the song I Wonder as I Wander is unworthy not ornery.

Maybe it is an intentional mispronunciation as a marketing ploy. A small cafe in my neighborhood recently displayed a sign advertising flotes. The elementary school across the street politely asked they correct the misspelling. No go, said the cafe.

If it is indeed a marketing ploy, it's surely worked. We've all been exposed, and who knows how many others are talking to their linguaphile friends about the ad.