The way we speak will always be a focus for anxiety. It's because it encodes so much of what is important to us: where we come from, what social class we belong to, who we want to be like. It's not surprising then, that people worry about losing these indicators of identity. As culture becomes increasingly globalised, will the accents that marked communities out as different disappear?

At this point some definitions might be helpful. A very good one is the Yiddish phrase a shprakh iz a dialekt mit an armey un flot, which means "A language is a dialect with an army and a navy". It's a useful reminder of how arbitrary linguistic divisions can be. Some languages, like Danish and Swedish, or Hindi and Urdu, can be understood by both sets of speakers without a problem – they are mutually intelligible. This isn't the case with many "dialects" of Chinese.

To avoid getting into political muddles, linguists tend to think of all varieties of a language as dialects. The test for whether a particular dialect constitutes a separate language or not is usually mutual intelligibility.

So where does this leave "accent"? It's really an informal way of talking about the most striking aspect of any dialect: the way its sounds differ from the ones we're used to. In any dialect there will also be differences in word order, meaning and vocabulary, but these might not be so obvious at first. What we notice immediately are the patterns of intonation and the vowels and consonants (think of the Geordie pronunciation of "town" or the friction in the "k" at the end of words in Scouse).

Does modern life mean that all dialects of English will be smoothed over? Not necessarily. People may play up differences that have a useful social meaning. But for varieties kept distinct by remoteness or a way of life that is disappearing, the future looks uncertain. Here are some of the most fascinating:

Tangier

Reading on mobile? Click here to watch a video about the Tangier, Virginia accent

It's isolation that breeds linguistic difference. Just like an animal species on an island, a dialect that has little contact with the outside world will evolve in unpredictable ways and may give rise to forms found nowhere else. It may also hold on to features from earlier stages of the language that have been wiped out elsewhere. This seems to have be the case in Tangier, a remote village in Chesapeake Bay, Virginia. Though it may not be "Elizabethan English" as some claim, it's a reflection of a lifestyle that has changed relatively little in the past few hundred years. With traditional occupations disappearing and more Tangier residents commuting to the mainland, however, it is unlikely to survive for long.

Forest of Dean



Reading on mobile? Click here to view a clip of Blue Remembered Hills

The Forest of Dean is a district in the west of England that has maintained a separate cultural identity, partly because of a strong tradition of employment in local industries like forestry, ironworking and mining. The way Forest people speak owes much to this heritage: there is a rich vocabulary related to these skills, now mostly forgotten. In 1962, Dennis Potter, who wrote the TV play Blue Remembered Hills in dialect, described it thus: "It is a rich and very heavily flavoured mixture of the speed and lilt of the Welsh borderland, the broad, lengthened vowel sounds and buttery emphases of the West Country and many distinctive local words and rhythms of its own."

Cockney

One of the most celebrated English dialects, a variety spoken by working class east Londoners – famous for its playful vocabulary as much as for the way it sounds – is likely to disappear within a generation, according to one sociolinguist. His studies suggest it is being replaced by Multicultural London English. In an age where travel and migration are much easier, we need to be understood by a broader range of people, and tend to temper the most distinctive features of our accents. But what, precisely, is being lost?

Reading on mobile? Click here to listen to a man speaking with an east London accent

Listen to Mr Kent, born in Hackney in 1888, recorded in 1967 – and see if he conforms to your idea of what a traditional east London accent actually sounds like.

New York

One of the most distinctive features of traditional New York speech is that r isn't pronounced, except where the sound comes before a vowel. This is called "non-rhoticity", and can be heard in the "Noo Yawk" accent we know from the movies. But it's been on the wane for a while. Why? There's a clue in William Labov's classic 1966 study of how accent and social status interact. He gathered evidence in Saks, an upscale department store, and compared it to data taken from Macy's (middling) and S Klein (working class). He found that, the higher you went, the more the r was pronounced. When his study was repeated in 2009, the same pattern was found, but non-rhoticity was even harder to find. That aspect of the accent has been stigmatised – and may not last another generation.

Cajun

Reading on mobile? Click here to listen to a Cajun English accent

Cajun English, spoken only in southern Louisiana, is a dialect strongly influenced by French and something of a historical oddity. The Cajuns themselves are said to be descendants of French settlers of Acadia (now Nova Scotia, Canada), deported by the British after 1755. Cajun sticks out among other southern dialects, with shorter vowels and a very unusual feature in English – the non-aspiration of p, t and k (meaning the word "top" might sound very like "dop").

Lincolnshire

Reading on mobile? Click here to listen to a Lincolnshire accent

Like many rural dialects that developed in an era when travel was greatly restricted, the strongest versions of the Lincolnshire brogue are dying out. A fine example is provided by the Wink brothers in the clip above.

Yola

Reading on mobile? Click here to listen to a song in Yola dialect

Here's one so endangered it's actually, well, extinct. Yola was a variety of English that evolved in Wexford, Ireland, after the settlement of the county by Norman Welsh, French and Flemish migrants from the 12th century onwards. As the song in this clip shows, it's impossible for a speaker of modern English to understand more than the odd word. In Yola, the stress fell on the second syllable of many words, such as "dinner" and "reader". It survived into the 19th century, but was gradually subsumed into Hiberno-English.

Philadelphia

Reading on mobile? Click here to listen to a Philadelphia accent

Another endangered big-city accent? The way they speak in Philly has long been a source of fascination to outsiders. It's a difficult one to imitate. But is that uniqueness being lost? Well, yes and no, say researchers. Some aspects of the pronunciation, such as the diphthong in words like "fight", are becoming more marked. As researcher Joe Fruehwald explains, the accent isn't fading away, but evolving.

Which leads us to our conclusion. What are the most endangered accents of English? They all are, really. No accent or dialect is ever preserved in aspic: for example, no one really speaks received pronunciation as it was originally conceived any more – not even the Queen. Changes in the way we pronounce things ripple through populations, setting off further unpredictable changes with their own knock-on effects until things get very complicated indeed. If you've ever wanted to meet a speaker of an endangered dialect, just look in the mirror.