My main hobby is choral singing. Learning IPA is insanely helpful; at a high level the pronunciation of words really really matters and making sure the choir place the vowels (and turn the dipthongs) in the same way is a big deal (think of Anthea Turner singing 'fire' in a pop song compared to a baroque English 'fire').

I've noticed consistently that more British people are familiar with IPA, even passingly or badly, than Americans. I've never quite known why -- unless you do a language degree here you're never taught it formally, but it's usually in the dictionaries (e.g. the Oxford English dictionary) by every word, often with multiple forms for different geographic regions. I've never actually seen a real physical en-us dictionary -- does Marriam Webster (sic) do the same?