Saw this one on the outside of an old-style school building while working as an Election Inspector in the recent primary.
I’m guessing: the person who typed this up heard the word, but never encountered it in actual use.
The correct word, of course, is annunciator, as defined there. Not exactly a homonym, but a pretty close match.
Wrong word, used properly, and spelled correctly. It’s not like I’ve never made that sort of mistake, fer shure!