If you google this line: "family guy" "who can hear stewie" there are several pages on the matter, with most of them (annoyingly) having a dead video link within them. That video showed the answers given at Comic Con 2011, by the show's creators, in response to the same question that you've asked. However the text of their answers is also included on this page:...
If you google this line:
"family guy" "who can hear stewie"
there are several pages on the matter, with most of them (annoyingly) having a dead video link within them. That video showed the answers given at Comic Con 2011, by the show's creators, in response to the same question that you've asked.
It depends on the episode. If it advances the story that folk understand him, then they will. Otherwide they don't. Don't try to be rational or logical. Where it works, it works.