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
Bernese German phonology seven diphthong phonemes: The number of phonetic diphthongs and triphthongs is significantly higher, since all monophthongs (except for short , , , ) and all opening diphthongs may be followed by a (from vocalized ), for instance → ('stable'), → ('steel'), → ('feeling'). Additionally, there are certain combinations with , for instance ('toil') or ('turns' from 'to turn'). In southern Bernese German (not in the city of Bern), the closing diphthongs merge with the near-close monophthongs to , for instance instead of ('cloth'). This phenomenon is also found in the neighbouring Bernese Highlands and Sense District dialects. In northern Bernese