I've had this problem on my desktop since 10-24. I can literally put the dictation on and just let it run until it shuts itself off, and it will create a string of these words. Words and phrases that I've gotten so far include:
“catch,” "catchup," "catchy," "catcher," "A Chachi," "Chatchai," “are chips,” “or Chata,” “or chat,” "achieve, Kate, " “are Chuchu,” "Katje," “are Chachi,” “are Chachi a Chachi,” “Are Chatchai,” “are Chachi catch,” “Catch up catch,” “Are catching,” “catch up,” “Catcher catch,” “Catching,” “capitol catch," “a Chuchu,” “a Chachi,” “are Chutcha,” “Achoo,” “catchup,” “Can,” “Catch that,” “a Chachi catch,” “A chachos,” “a Chachi, catch up,” “Catch up catcher catch up,” “Catchy catcher,” “are Chachu," "are cheap," "or check"... the stranger ones once or twice, the simpler ones multiple times, the simplest ones many times.
There's no confusion whatsoever about this being an Apple issue; there's nothing else it can be, with multiple people getting it repeatedly on different devices and operating systems. I get it with every browser, every application, EVERYWHERE. Even dictating a search term in the Finder! This could also be the result of a hacker, I guess, although you'd think that Apple would catch onto that pretty quickly... No pun intended!