you know I sometimes think the distinction between ass and arse is so much about the distinction between Aust/British and USA cultural moods. Arse is vulgar British slang for bottom (how the dictionary terms it). Somewhere along the way, Americans changed the pronunciation and then the spelling followed to match the pronunciation. It has a similar slang effect in both cultures.
But when I say 'ass' instead or 'arse', I really can't say it without feeling so American. It is like Americanism is embedded in the the difference. Just saying ass transports me into that broad accent Americans have. And soon I'd find myself saying kick-ass, and then I'm in the Marines.
'Arse' is no less or more a punchy vulgar slang word in Australian culture, but the 'r' changes the sound away from American to Australian or British cultural mood. It's quite strange. the absence of the 'r' causes the voice to sound that flat hard 'a' sound with the mouth stretched sideways like in a smile. Whereas adding in the 'r' softens the 'a', which allows the guttural use of the word to have more bass, and throat gurgle, which could never be done with ass. But ass has its own 'nasty' touch.
What is also curious is that mostly, American tonality emphasises the 'r' in words, which allows American accents to have a rich rolling sound which is often very sensuous. Whereas Australian tonality is more often flat and hard. I sometimes wonder if that is why America often produces voices that are very deep and rich, which I never hear in Australia, or Britain for that matter. But that is exactly the opposite of the ass/arse situation.
