Triphthong

From KneeQuickie

A triphthong, like a diphthong, is a vowel sound that changes height and frontness as it is pronounced; unlike a diphthong, this change is not just in one direction, and therefore can only be accurately specified by naming three positions, not just where it starts and ends.

As with diphthongs, triphthongs are usually written in the IPA and X-Sampa simply by placing the symbols for the initial, middle, and final positions next to each other; an alternative is to join them with two tie-bars.

Triphthongs are a rarity in natlangs. Most notably, they occur in the RP dialect of English: for example, "ire" is pronounced as a triphthong, /aI@/.

Like diphthongs, triphthongs vary as to whether the first or second vowel is stressed (with triphthongs, the third vowel could be stressed, but this never occurs in natlangs). I know of no standard terms for these types of triphthong; they could perhaps be called primary and secondary triphthongs. All triphthongs in English are primary; Spanish is an example of a language with secondary triphthongs.