Supraregionalisation in Ireland
Supraregionalisation is an historical process whereby varieties of a language lose specifically local features and become less regionally bound. Supraregional varieties (of English in the British Isles) are found in northern England, Scotland and Ireland.
Take the north of England as an example: this is a region which has a geographical and cultural identity of which speakers are aware. There is clearly a northern type of accent in England and this arose through a set of local features being used across the subregions of the north and kept to by non-local speakers for identification purposes vis à vis the south of England.
Supraregional (non-local) features
[a] in BATH lexical set [ʊ] in STRUT lexical set
Historically, supraregional varieties have arisen through the suppression of vernacular features leading to forms of a language in which there is less variation than in local speech, e.g. general northern British English.
Supraregionalisation in Ireland
A supraregional variety can also arise through the adoption of a geographically confined variety by sections of a population spread over a much larger area. In such cases the variety which triggers this process stems from a source which has prestige in the society in question, typically the capital of a modern nation state. This is what has happened in the Republic of Ireland over the past 15 years or so where changes in Dublin English have spread to the entire country.
The 1990s new pronunciation of southern Irish English involves above all the realisation of vowels and of the liquids /l/ and /r/. Other segments do not seem to be affected by the shift in pronunciation. However, two points should be emphasised in this context,
1) The dental stop realisations of the THOUGHT and THIS lexical sets, which has been part of the supraregional variety of English in the south of Ireland since at least the beginning of the 20th century, are maintained in the new pronunciation.
2) Among young female speakers, especially in Dublin, there is a slight affrication of /t/ and /d/ in syllable-initial position. This may be an age-grading phenomenon which disappears with full adulthood. It is certainly sub-phonemic at the present. However, it is difficult to predict the course of such developments.
Back vowel raising
In its original form in the capital, the Dublin Vowel Shift consists of low vowel retraction and low back vowel raising. The only exception to this general movement in vowel space is the non-rhotic long low vowel in the BATH and DANCE lexical sets. This vowel is always [a:] in Irish English. A retraction to [ɑ:] would be seen as an adoption of an English accent and has always been regarded as unacceptable for the native Irish, indeed speakers with this retraction, are ridiculed as having a ‘grand [grɑ:nd] accent’. Probably, for this reason it has not been participating in the general retraction and raising of the Dublin Vowel Shift.
When comparing the new pronunciation with conservative mainstream Irish English it is remarkable that a merger has occurred, the lack of which has hitherto been a prominent feature of Irish English. This is the FOR-FOUR-merger where the formerly distinct vowels /ɒ:/ and /o:/ have collapsed due to the raising of the former to [o:], its realisation in new Dublin English today.
Hickey, Raymond 2013. ‘Supraregionalisation and dissociation’, in: J. K. Chambers and Natalie Schilling (eds) Handbook of Language Variation and Change. Second edition. Wiley-Blackwell, pp. 537-554.