1. There are going on for 400 million native speakers of English worldwide. All but the very least educated have relatively little difficulty in understanding the English of any of the others even though there are very obviously quite considerable differences between the forms of spoken English used by different groups. People are usually instantly aware that they are hearing a different accent from their own. Sometimes they like the different accent or are impressed by it. Some kinds of foreign accent are widely regarded as chic or charming, some as quaint or clumsy. There is certainly a pecking order though the ratings depend very much on the listener's own background. European accents are at the upper end of the scale with French probably the most popular as witness the success of film actors going back to Charles Boyer and Maurice Chevalier. Scandinavians like Garbo and Ingrid Bergman have also been very popular. Within Britain the accents of large industrial centres such as Glasgow, Liverpool and Birmingham tend to have the least prestige. Rural accents generally produce fairly favourable reactions.
2. Accents considered "harsh" tend to be less popular eg ones with any obtrusively "guttural" sounds ie vigorously articulated uvulars or fricative velars. The vigorous alveolar trills of eg many varieties of Arabic may seem harsh to most English speakers. Even speakers of Scottish varieties of English, although often credited with "trilling all their r's", in fact only relatively weakly articulate most of them and leave out far more than is popularly supposed. Most forms of English have typically quite weak articulations corresponding to the < r > letter of the spelling when it stands for any sound at all. London English weakened the r's occurring before consonants so much that by the end of the 18th century they had for the most part all disappeared. To this day presence versus absence of / r / is the most striking difference between the most general kinds of British English on the one hand and of the most general form of American English on the other.
3. A speaker of General American can be expected (with a fair amount of optimism) to utter a sound corresponding to virtually every < r > of English orthography whereas the speaker who uses the General British (or so-called "Received") pronunciation will only utter about half the number of r's. General American is spoken by about two-thirds of the US population: the other third live either in the coastal east or in the "Deep South" in which latter area "dropping" of / r /goes the furthest it does in the whole of the English-speaking world because they don't even make much use of linking / r /, that is the / r / that most English-speakers use most of the time in expressions like later on, pair of etc. The GA "r-keeping" pattern is also to be heard in southwestern England and to some extent in counties adjoining the border with Wales, in various non-metropolitan parts of west midland and northwestern England, in Ireland, in Scotland, in Canada and in some Caribbean islands. The General British pattern in this regard is to be found over most of England, in Australia and New Zealand, in the mothertongue English of Africa and in much Caribbean English.
4. Among the other usually articulatorily weakest items in the English inventory of sounds are those characterised by writers on English phonetics as "approximants" viz / l, j, w / and / h /. The last of these, / h /, has become a "shibboleth" or marker (of education or the lack of it) par excellence. Few local accents in England keep it as a "natural" feature but it is hopelessly unfashionable to omit it from the beginning of a stressed syllable in all but a handful of words. In unstressed syllables its absence will usually pass unnoticed: indeed the enthusiasm for including it every time in eg He helped him hide his hedgehog would be likely to betoken social anxiety. Almost nobody in England now uses an / h / in words like why and where though most Irish and Scottish people and many Americans do. On the other hand General American speakers usually omit the yod from tune, due and new etc. In England to do so would be a mark of an East Anglian or other local accent except in a few mainly unstressed occurrences of words as in New York or in a simplifications of sequences like last year which for many people readily becomes homophonous with last ear.
5. The other single most striking differentiator of kinds of English is probably their treatment of words like bath, ask and dance. In southeast England, in New England, in Africa, in much of Australia and in New Zealand they all share the "broad" vowel of calm. However, in the north of England and much of the Midlands and in parts of Australia they have the "flat" vowel of cat. In Ireland, in Scotland, in the USA and Canada, they too have the "flat" vowel in such words and also in half. Thus the GA form of halves coincides with haves (as opposed to have-nots). The words can't and aren't (derived from am-not ) are least often "flattened" around the English-speaking world. Other similar groups of words are the cloth, cross, cough group which have a relatively long vowel in GA but a relatively short one in GB etc. This feature was characteristic of Victorian General British English too but mainly died out in England by the 1920s. Other directions along which the mainstream accents of British and American English have diverged since the last century include the endings of words like docile, fragile, dictionary, territory and matrimony which now have different strengths in their post-tonic vowels in America. American English has also a marked preference for end-stressing of French-derived and even other exotic words such as garage, chateau, crochet, plateau etc. See our Section 3.1
6. No doubt because Scotland was a separate kingdom until the 17th century, most Scottish varieties of English display forms more sturdily independent of all the other varieties of English than one can find in any other area of the English-speaking world. Very strikingly they may incorporate no contrasts of vowel values in a phrases like good food, Sam's psalms and ought not. They all have an extra consonant phoneme /x/ in words like loch.
7. At p. 349 Wells (1982) remarks that about half of the English speak with some degree of northern accent. Educated Northern English has mainly only moderate differences of pronunciation from southern usages. The most pervasive northern characteristic that contrasts strongly with the whole of the rest of the English-speaking world is the preference for a 'clear' vowel in unstressed prefixes that constitute closed syllables (ie end with a consonant sound) in words such as advise, contain, example, observe, success. Where the unstressed prefix ends with a vowel sound, northern usage is no different from that of the rest of the English-speaking world eg in words like apply, connect, effect, oblige, suppress etc. See our Section 7.4.
8. In Yorkshire alone there is widely to be heard the unique phenomenon within the English-speaking world in which the final soft consonants /b, d, g, ʤ, v, ð , z, ʒ / of a preceding syllable are habitually converted to their corresponding sharp equivalents /p, t, k, ʧ, f, θ, s, ʃ/ under the influence of a following sharp consonant. This phenomenon can be observed in more general forms of English in variant versions of the words breadth, width and length and in used-to, have-to and supposed-to, but in Yorkshire it happens widely though least among the most educated. Thus Bradford is locally regularly pronounced as if it were spelt Bratford and broadcast similarly. So also with Good Friday, Grand Theatre etc but, although slight traces of the tendency are to be heard even in highly educated Yorkshire speakers, extensive use of it is more characteristic of uncompromisingly "plain" speakers like Arthur Scargill, the miners' union leader who has appeared to say eg dock population for dog population.
9. In the cases of individual words the LPD lists Educated Northern English versions of eg among, ate, because, breakfast, eighteen, eighty, exam, exhaust (as a noun), gooseberry, mischief, none, nothing, once, perfect, raspberry, says, terrible, us, with, yesterday with forms which are not normal in the south. Yet other words have predominant forms in the north which do also occur in the south but usually as fairly uncommon variants eg comfortable, constable, interesting, magazine, Manchester etc and, until relatively recently, Asia and the noun dispute.
References:
Wells, J.C. (1990). Longman Pronunciation Dictionary. London: Longman Group UK Ltd. ("LPD")
Wells, J.C. (1982). Accents of English. (3 vols) Cambridge University Press, Cambridge, UK.