Classical Arabic has two diphthongs, realised as the long vowels and, respectively, which developed further into and, respectively, in urban North African dialects. Some notable exceptions to this monophthongization are some rural Lebanese dialects, which preserve the original pronunciations of some of the diphthongs. Other urban Lebanese dialects, such as in Beirut, use the mid vowels and. Another exception is the Sfax dialect of Tunisian Arabic, which is known mostly for keeping the Classical Arabic diphthongs and.
English
Some English sounds that may be perceived by native speakers as single vowels are in fact diphthongs; an example is the vowel sound inpay, pronounced. However, in some dialects is a monophthong. Some dialects of English make monophthongs from former diphthongs. For instance, Southern American English tends to realize the diphthong as in eye as a long monophthong. Monophthongization is also one of the most widely used and distinguishing feature of African American Vernacular English.
Smoothing
In Received Pronunciation, when a diphthong is followed by schwa, a series of simplifying changes may take place, sometimes referred to as smoothing. To begin with, the diphthong may change to a monophthong by the dropping of the second element and slight lengthening of the first element:. The vowels and, whose usual forms are in fact slightly diphthongal, may undergo the same change and become. Next, the following schwa may become non-syllabic, forming a diphthong with the preceding monophthong. In certain cases, this diphthong can itself be monophthongized. Thus the original sequences and can end up as simply and. For example, the citation form of the wordour is, but in speech, it is often pronounced as , or as a monophthong. Similarly, fire can reduce to or.
In Hindi, the pure vowels and are written with the letters for the diphthongs ai and au in Devanagari and related alphabets. The vowel sequences and exist in Hindi, but are written as āi and āu, with long initial vowels.
German
The so-called early frühneuhochdeutsche Monophthongierung is particularly important in today's Standard German. It changed the diphthongs ie , uo and üe to respectively ie , u and ü : before 11th century > nowadays liebe > liebe guote > gute brüeder > Brüder The digraph "ie" has kept its spelling despite monophthongization. The New High German monophthongization started in the 11th century in the center of the German-speaking area. Bavarian and Alemannic dialects in the south did not undergo the monophthongization changes and thus these dialects remain in an older language state.
Greek
underwent monophthongization at many points during its history. For instance, the diphthongs monophthongized to around the 5th century BC, and the diphthong monophthongized to in the Koine Greek period. For more information, see and Koine Greek phonology.
French
underwent monophthongization and so the digraph, which formerly represented a diphthong, represents the sound or in Modern French. Similarly, the digraph and trigraph represent the monophthong due to the same process.
