Like a cross between a Moon Unit Zappa and “Snake” from the Simpsons. 
OK they’re caricatures, but there are definitely certain vowels that are recognisable from those stereotypes.
I used to speak to my American friends around Christmas time every year. (Folks I had known from the Internet). Each had an accent which was similar. I did find that the person I spoke to from Wisconsin had a stronger accent than the person from Georgia which came as a bit of a shock (to me- based simply on what I had heard). Mind you they seemed to have difficulty with my accent, describing me as sounding like I was talking inside a submarine. That was probably the kindest.
As for Australian regional accents, South Australia is certainly different (there was a thread on this years ago).
You can almost always tell when someone’s from New South Wales, but.
And from North Queensland, hey?
I’d actually be very interested in what you mean by the word “flat” in this context. It’s something I’ve seen Americans use quite often if reference to accents, but it doesn’t mean anything to me at all. Or rather, it does, but I would usually take it to mean an expressionless monotone, which doesn’t seem to fit, in context.
But I think that what you’re observing is a difference in attitude towards, and perception of, accents, rather than a difference in the range and types of the accents themselves.
There certainly is a “standard” English (though not British) accent, and it’s Received Pronunciation (though I’ll need to clarify here that RP, like any other accent, actually covers quite a range – precise definitions of what is, or is not, RP vary, and change over time).
The difference, it seems to me, is really in the perception that the standard accent is an accent itself, rather than the lack of one. Which is why I think you must surely be wrong about Americans not being able to recognise or imitate Standard American English – you just don’t think of it that way. Americans talk in terms of “losing an accent” or “speaking with less of an accent”, but what they’re actually doing is adopting, or imitating, SAE.
Is that a NSW thing? I thought it was a you kids get off my lawn thing.
I don’t know, but.
I’m in Minnesota and its pretty indistinguishable. Until they say about. And then all of a sudden its “oh, you are from Canada.”
The strange thing is that they almost always are surprised at this point that you realized it, they don’t hear it.
(There are different Canadian accents as well - particularly Quebec)
Oh it’s definitely a NSW thing. I’ve been back in Adelaide for 7 years and it still pops out occasionally, and I get told off by my family.
Yes
No. The most non-accented American accent to my ears is Mid-Atlantic, but most of the US newscasters I’ve heard have a Midwestern, Californian or Northeastern accent. Mid-Atlantic seems more prevelant with actors.
I can recognize many other US accents - I think of them as GenericMidWestern, StereotypicalSouthern, West Coastish, N’awlins, TwinCitiesMidwestern (this may be a milder form of Yooper, I think. People who say “Oh, yah!”) NewJerseyYorkian, Bawstonic, StephenKingian, Hillbilly, AfroAmerican and YiddishAmerican. And that’s just from Americans I know.
But all English Canadians sound alike to me…
What? I know plenty of people who have the same accents as newscasters (who don’t all have exactly the same accents anyway). They just don’t have the same bullfiddle voices and the odd singsongy rhythms.
ok, now I’ve got to post this:
(coarse language within)
I don’t think it’s a NSW thing. I know only one person who ends his sentences with ‘but’ and he gets a lot of grief* at work because of it.
- good natured ribbing
I can identify New York, and differentiate the south from the midwest, Baltimore, plus a few others…and yes, they all sound different to the generic sounding newsreaders on CNN or whatever.
Mid Atlantic, like Katherine Hepburn and Cary Grant? I am not trying to correct you, I just want to know. The label gets applied to a host of accents at times.
I thought he meant mid-western USA and mis-spoke. Mid-Atlantic is different. Cary Grant had a different accent to most people I’ve ever heard on film.
I wouldn’t call Hepburn Mid-Atlantic. Her accent is traditional northeastern upperclass.
Basically what I take it to mean is that most Americans will have two accents that sound “natural” to them- SAE, and their own regional accent. To myself, a Bostonian, I hear both Boston accents and SAE as “normal”- that is, I am not jarred out of the conversation by thinking “that person has an accent!” Another part of it is that most regional accents are variations on SAE- Bostonians drop the R, Canadians say “aboot”, Southerners drawl, etc. etc. (Obviously this is a gross oversimplification but you get the point).
I guess, in essence, it’s not literally a flat monotone- it’s just that that person’s accent is so generic that they can’t be placed any more specifically than “American”, even by Americans.
People I have heard use it are:
Bogans, or;
Bondi born and raised kids.
So what do I know? 
Midnorth coasters are bad for it as well
This assertion by Americans–that Canadians say “aboot”–has always bothered me, especially since no Canadian I’ve ever known (bar one or two from the Atlantic Provinces) has ever said “aboot.” Could one of our American Dopers point to any audible media (Canadian news videos, Youtube. or whatever), where a Canadian says “aboot”? Maybe we can put this myth to rest; or at least present a defense (i.e. the speaker is using a regional variation, on par with Boston English or Texan English). Having never heard “aboot” in my life, except for that coming from certain speakers in the Atlantic Provinces. despite spending all of my life in English-speaking Canada, I would be really interested in hearing how Americans claim that we say it.
I will say that certain Americans of my acquaintance pronounce “about” widely–that is, more widely that we do. “Abowwt” is the best I can render it, and it is certainly different than Canadians pronounce it; but even then, who can say that the Canadian pronunciation is incorrect?
FTR, my own personal accent is such that I have been asked what part of Chicago I come from. I do not come from Chicago, but apparently, I sound like I am a Chicagoan–my (to Americans) apparent Canadian requirement to say “aboot” notwithstanding. Nobody in the US has ever pegged me as anything other than an American, and likely from Chicago.