Triphthongs

Diphthongs are vowels that have a start point different from their end point. Triphthongs get from the start point to the end point via some other, third, vowel in the middle. Or, alternatively, they are diphthongs with a vowel that forms an extension.

Triphthongs have been described for RP in words such as ‘fire’ and ‘power’, i.e. diphthongs which are followed by an  in the spelling. These words are pronounced monosyllabically with triphthongs such as  and  ; but they are also susceptible to ‘smoothing’, giving pronunciations such as [fa:] and [pɑ:] respectively.

Triphthongs also occur in southern US varieties. For example, in Alabama, the vowel of MOUTH is produced as  , that of CHOICE as  and that of SQUARE as .

Triphthongs are a more controversial unit than diphthongs, because they are not considered to have a phonological status. In RP, triphthongs can be analyzed as diphthongs + phonemic /r/. The Alabaman triphthongs can be thought of as complex realizations of simpler underlying phonological units. Tripthongs can, at least in some varieties, distinguish words. For example, in RP, ‘hire’ (one morpheme) has a single syllable,  , and never two; but the word ‘higher’ (two morphemes, ‘high+er’) can be disyllabic,  , which ‘hire’ cannot be.