Ben, I don't have your experience of travelling in Asia.  I accept it as a historical fact that English is widespread in many parts of Asia as a result of British imperialism.  Unfortunately, this imperialism involved stealing the land and suppressing the civil rights of other peoples.  This was the worst possible foundation for a cultural exchange on equal terms, and obviously in practice it was a one-way cultural transmission process.  

This period of history is thankfully over, though many countries may reasonably accuse the UK of being a little too quick to move on from its long-term consequences for formerly colonised nations.  And so, it would not be surprising if many people in Asia have an ambivalent attitude towards the English language, and the accent of the British ruling classes. 

Every student is different, so a well-rounded teacher should be familiar with every tool available. Combining visual, auditory, and yes, muscle memory will get the best results in the shortest time. The IPA symbols relevant to English can be learned in no time, and will definitely pay big dividends. It’s a tool for aspiring polyglots, not just language nerds.

Of course you should teach students how to use their lips, tongue, vocal cords, etc to articulate the sound. At the same time, English spelling is etymological, not phonetic, which means many students find it useful to have the IPA as an aid to knowing when to make the sounds. Listening practice (active listening and repeating) is essential, however, it takes a while to train the ear to recognize the new phonemes (and their actual phonetic realizations). In any event, it’s not always convenient to consult an electronic dictionary, and the IPA allows us to understand the sounds with just a quick glance, instead of having to listen again and again. Likewise, IPA allows students to take notes “in the field” as to how English really sounds in their local area.

Thanks for the replies so far, Camilo and Laurence.  

The phonemic chart is a tool but I agree that many people have reached a high level of English without it.

On the other hand, when students get frustrated at not being able to understand speech or reproduce a word like a native speaker, then for me, the IPA has a role in analysing the problem, and reaching a solution.

I teach many Spanish and Italian speakers and many have problems identifying a word like "organisation", in speech, despite its close similarity in spelling and meaning to the equivalent in their languages.  Some who can identify it, still can't reproduce it.  For me, they need help to train their ears and learn that English phonetics does actually follow systematic patterns.

If I just say the word "organisation" in my own (London) accent and say that's standard, students won't always really trust me. For them, it could be just my own individual preference.  But if they have the tools to see the phonemic transcription in the dictionary and produce it themselves - just like I said it - then real progress can be made.

They can even then see that the way Americans and English people say e.g. "organisation" is not so different (ɔːɡənaɪˈzeɪʃən UK, ɔrgənaɪˈzeɪʃən US), and start to identify the known differences across accents, as well as what they have in common.

I accept that not all teachers are interested in using it, so students who are not convinced of its value will probably find support for their view from plenty of teachers!  This may be a big part of the problem for people like me who believe in it.

Sorry, excuse my spelling errors!! Malarkey*, couldn't*, familiar*! A little more:

Now, some sounds are just hard to pronounce. In English, some people have trouble with the "th" sound, in French perhaps it's the ü. At this point, you can explain that you put your tongue between your upper two front teeth and blow (for the "th"). The student then needs to go and both practise this again and again and again as well as listening out for it (this is more important than you think) whenever they hear it in the (hopefully) vast amounts of listening they are doing, as this will help them imitate it more accurately.

However, some things the student just won't hear and this is where the teacher can come in handy. But even though the teacher helps, it's still the student that then has to go away and listen carefully lots and lots of times.

I actually don't believe people that tell me "they can't get rid of their accents". The amount of times Russian people (I don't want to pick on Russians, they just prove my point well) say "Rrrrrrrrrrrussia" with a rolled "r" or "zzzis" for "this" is amazing. I once said to a student "have you EVER hear ANYONE pronounce it like that before?!". He said no, so I said back to him "well why on Earth are you pronouncing it like that then?!". Another good example is Japanese people trying to say "bridge". They are influenced by their own "syllabary" system, and it therefore becomes "brr-ree-gee".

All you need to do is pay attention.

Michael, perhaps unwittingly this remark of yours is a powerful comment on the state of the Commonwealth and that of the BBC, "Most students don't reach a C1 level."

I don't want to sound renegade or politically incorrect, but as I travel the world, especially in Asia, I cannot but marvel at the number of non-British people in their 70s who were entirely locally educated but speak beautiful English, in Hong Kong (until 1997 a British colony), Malaysia, India, Singapore and even Thailand and Burma.  The reasons:  British English teachers and a BBC World Service which still insisted on RP.  "This is the BBC from London" was for many of these boys and girls the reassuring prelude to beautiful English and reliable news.  The BBC World Service was a beacon of hope; it was both Mentor and Trusted Friend.

I don't want to sound renegade or politically incorrect, but there were many more British teachers and British people in these places up until the 1960s (?).  Nowadays not so many British teachers go, or are allowed to go, to these places to take up teaching and other jobs.  The great British retreat started in 1947 with independence for India.  When did the BBC give up RP to embrace diversity and "world English"?

This is not as much a digression as it seems.  Gentlemen and ladies from these countries in their 70s and 80s have told me that in the days when clever boys and girls went to local schools run by the Church of England, everyone knew IPA, and they were able to speak English to near-native standard by the time they were 14 years old.