Scottish vowel length rule

The Scottish vowel length rule (also known as Aitken's law after A. J. Aitken, the Scottish linguist who formulated it) describes how vowel length in Scots, Scottish English, and, to some extent, Mid-Ulster English and Geordie is conditioned by the phonetic environment of the target vowel. Primarily, the rule is that certain vowels (described below) are phonetically long in the following environments:

  • Before /r/.
  • Before a voiced fricative (/v, z, ð, ʒ/).
  • Before a morpheme boundary.
  • In a word-final open syllable, save for theHAPPY vowel /e/ (or, in Geordie, /iː/).


The underlying phonemes of the Scottish vowel system are as follows:

Vowel length

The Scottish vowel length rule affects all vowels except /ɪ/ and /ʌ/ and, in many Modern Scots varieties, /eː/ and /ɔː/. The further north a Scots dialect is from central Scotland, the more it will contain specific words that do not adhere to the rule.

  • /ə/, /ɪ/, /ɛ/, /a/, /ɔ/ and /ʌ/ are usually short.
    • In some Modern Scots varieties /a/ may merge with /ɔː/ in long environments. In Ulster Scots /ɛ/, /a/ and /ɔ/ are usually always long and the [əʉ] realisation of /ʌʉ/ is short before a voiceless consonant or before a sonorant followed by a voiceless consonant but long elsewhere.
  • /i/, /e/, /o/, /ʉ/, /jʉ/ and /ø/ are usually long in the following environments and short elsewhere:
    • In stressed syllables before voiced fricatives, namely /v, ð, z, ʒ/, and also before /r/. In some Modern Scots varieties, before the monomorphemic end-stresses syllables /rd/, /r/ + any voiced consonant, /ɡ/ and /dʒ/. In Shetland dialect the [d] realisation of underlying /ð/, usual in other Scots varieties, remains a long environment.
    • Before another vowel and
    • Before a morpheme boundary so, for example, "stayed" [steːd] is pronounced with a longer vowel than "staid" [sted].
  • /ɔː/ usually occurs in all environments in final stressed syllables.
  • /iː/ and /eː/ are usually long.
  • The diphthong /əi/ (1s & 10) usually occurs in short environments, vowel 8a, which occurs stem final, is always short, and /ai/ occurs in environments where /i/, /e/, /o/, /(j)ʉ/ and /ø/ are long.
  • The diphthong /ʌʉ/ is usually short.


The Scottish Vowel Length Rule is assumed to have come into being between the early Middle Scots and late Middle Scots period.

Uses material from the Wikipedia article Scottish vowel length rule, released under the CC BY-SA 3.0 license.