Vowel whose quality does not change over the duration of the vowel is called a monophthong. Monophthongs are sometimes called "pure" or "stable" vowels. A vowel sound that glides from one quality to another is called a diphthong, and a vowel sound that glides successively through three qualities is a triphthong. All languages have monophthongs and many languages have diphthongs, but triphthongs or vowel sounds with even more target qualities are relatively rare cross-linguistically. English has all three types: the vowel sound in "hit" is a monophthong , the vowel sound in "boy" is in most dialects a diphthong , and
Iau language [p̚] word-finally. /f/ is the only consonant that can occur word-finally. The low vowel is always nasalized, except when it is a component of a diphthong. The open-mid front vowel varies between [e], [ɛ], and [æ]. The following diphthongs exist: No diphthongs begin with /ɪ i i̝/ or end in /a ɔ/. There are two triphthongs: /aui/ and /aʊɪ/. The back components of these triphthongs are realized as unrounded. Syllables consist minimally of a vowel. They may include a single onset consonant and/or a single coda consonant. Diphthongs and triphthongs are attested. The template is (C)(V)V(V)(C). The tone-bearing unit is