About low-back vowels in American English

Hello, everybody! I'm a chinese from Beijing, and I'm learning American English as a second language. And I'm trying to learn the most general accent.

Sometimes I'm confused by the pronunciation of low-back vowels. I just find that not all Americans pronounce them in the same way. I'd be very very grateful if you help me with this problem.

Well, according to some dictionaries, there are two low-back vowels in AmE. And I picked these words for the two vowels respectively.
1. got, on, father, palm, ball, far, borrow
2. off, lost, caught, law, dog, fog, sorry, Boston, collar, wallet
However, I'm not so sure about this classification. Please help me!

Sorry, the classification above should be this:
1. got, on, father, palm, far, borrow, collar, wallet
2. off, lost, caught, law, dog, fog, sorry, Boston, ball

Though I'm not American, I'm familiar with some of these vowels as they mimic my pronunciation somewhat. So I would classify the ones I know as:

1. father, far, cot, collar
2. fortune, law, caught, ball, caller
These distinctions are typical of a New Yorker's pronunciation.

Referring to the first syllable of each word above:
In 1. This vowel is a very open "o" sound, close to "ah"
In 2. This vowel is a more closed "o" sound, a bit like a French ô, eau

*The a in hot, collar, far, mom, got, etc ocurrs in the front, not in the back , this is the same sound of the a in some spanish words like mama, papa, etc.

*now, i know that for some americans there's a difference between the vowel in hot and the vowel in on, but i pronounce both with the same long deep a sound that occurs in off,( law, raw, lost, cost,etc)

The major difference between Vowel 1 and Vowel 2 is simply a question of length and Stress. Vowel 1 is shorter and less stressed than the longer Vowel 2.
I think of Vowel 1 as either "ah" or "o", and vowel 2 as "aw" ou "au". For example even though spelling of dog has just an o, a lot of Americans spellit as dawg, which is closer to the way it is pronounced.
Vowel 2 is ocassionally pronounced at the end of a word, which never happens to vowel 1.
Law, spa, claw, raw, aw shucks, Paul, maul, ball, also, tall, off, cough

I love this topic. It is my favourite topic by far. It's the most challenging aspect of the English language in my humble opinion.

>Hear you have some links that will help you to understand the difference between those two vowels.

http://www.uiowa.edu/~acadtech/phonetics/english/frameset.html
http://www.soundsofenglish.org/pronunciation/ought.htm

> A considerable amount of americans don't have the deep o: in their vocabulary, their pronouce ball, law, cost, lost with the deep a: sound.
This is the most current pronunciation, visit encarta dictionary if you'd like to have some examples.

http://encarta.msn.com/encnet/features/dictionary/dictionaryhome.aspx

>Beware, a lot of websites that describe american pronunciation will tell you that all americans pronounce law with the o: sound , which , as i told you before ,is far away from the being true.

>American pronunciation is very complicated, there's a lot of different accents in US, so if you're watching tv for example, you could get confused .

>The a in not, hot, rock, pop, mom, etc is a front sound, identical to the spanish a.

Here in Mainland China, all kinds of books that teach American accent do not mention the so called "cot-caught" merger, and they describe the "aw" sound as a mid-open, back, and rounded vowel, which does not "sound American".

Later I started to watch an English teaching program, and surprisingly discovered that most American teachers pronounced "aw" very much like "o" or "ah". A Canadian teacher even merged them completely. Only one teacher from New York City made a clear distinction between them.

I think I should learn the "General American" pronunciation. So what should I do, merge or distinguish? Or change my accent often?

Standard American pronounciation makes a small but definite distinction between the two--that is, words like "ball, bought, caught" are pronounced with a slightly rounded vowel--bol, bot, kot (that's an approximation, using the ASCII phonetic alphabet).

Out West (including California) the caught/cot are unquestionably merged--either into kat or (less common) kot. The same holds true for two other regions--Western Pennsylvania and Northeastern New England--both both areas merge the two into kot.

Similarly, Canadian English almost always merges the two into kot.

Generally, though, the rule for General American English is to distinguish the two.

The simpliest solution is to simply pronounce all these sounds the same but lengthen and emphatise caught, law, bought, ball, caller, spa
and the you will be clearly understood by all Americans.
There are 3 distinctive NY accents. People from NY have the most difficulty being understood, even in America itself.

Yeah, I'm from Boston and have had trouble being understood while traveling in the United States.

There is a debate about what accent is "General American." People from suburban Chicago will tell you that they speak General American. People from suburban Los Angeles will tell you that they speak General American. However, people from suburban Chicago will not merge "caught" and "cot." People from suburban Los Angeles will. Nobody pays too much notice of it in the United States. The only things that will make others accuse you of not speaking General American is if you have a southern drawl or if you drop your R's and speak in some kind of East Coast accent.

<<Yeah, I'm from Boston and have had trouble being understood while traveling in the United States.>>
Wow, a native not being understood in his own country.

The reason why most of us Americans can't understand Bostoners is because they are r-droppers ''or is that ''r-droppas''.

Australians drop their r's. Cand you understand them?