There was a thread in GA about this question, again, and it got closed before I got to ask one of my own. Where did people get the idea that a duck’s quack doesn’t echo? I didn’t see anything about the origin of this odd belief in Cecil’s column.
Er…this column, of course. http://www.straightdope.com/classics/a5_071.html
I wish we could figure out where these things start, so we could find the person and drop him/her down a deep well. Or hang them up by their thumbs. Stoning, too, would be good to revive.
The most likely explanation is that some jackass thinks its funny and tells all his/her friends (both of them), who tell their friends, and the magic of exponential growth (and nowadays, the internet) spread the inanity over the planet.
The question appears first on Usenet in early 1997, about a year before Cecil wrote the column. It was part of 20-40 questions that were mostly facetious.
No one knows why