Interesting survey, and pretty reasonable results. It's a little surprising that chirping birds have become the convention if as few people 'hear' them as your mini-survey shows. Otoh, why are Xs for eyes a cartoon convention for being dead or at least unconscious?

The times I've had the wind knocked out of me, which mostly happened when I was a kid, involved falling down, never blows to the solar plexus. I've occasionally wondered about that too. Thanks for the link.