Monophthongization is a sound change by which a diphthong becomes a monophthong, a type of vowel shift. It is also known as ungliding,[1] [2] as diphthongs are also known as gliding vowels. In languages that have undergone monophthongization, digraphs that formerly represented diphthongs now represent monophthongs. The opposite of monophthongization is vowel breaking.
Classical Arabic had two diphthongs, pronounced as //aj// and pronounced as //aw//, which are realised as the long vowels pronounced as //eː// and pronounced as //oː// in numerous Arabic dialects. This monophthongization has further developed into pronounced as //iː// and pronounced as //uː//, 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 pronounced as //eː// and pronounced as //oː//. Another exception is the Sfax dialect of Tunisian Arabic, which is known mostly for keeping the Classical Arabic diphthongs pronounced as //aj// and pronounced as //aw//. Some varieties might maintain the diphthong for words recently borrowed from Standard Arabic or use them in free variation.
Some English sounds that may be perceived by native speakers as single vowels are in fact diphthongs; an example is the vowel sound in pay, pronounced pronounced as //ˈpeɪ//. However, in some dialects (e.g. Scottish English) pronounced as //eɪ// is a monophthong pronounced as /link/.
Some dialects of English make monophthongs from former diphthongs. For instance, Southern American English tends to realize the diphthong pronounced as //aɪ// as in eye as a long monophthong pronounced as /link/,[1] [2] a feature known as /aj/ ungliding or /ay/ ungliding. Monophthongization is also one of the most widely used and distinguishing features of African American Vernacular English.[3]
Smoothing is a monophthongization of a closing diphthong (most commonly pronounced as //eɪ, aɪ, ɔɪ, əʊ, aʊ//) before a vowel that can occur in Received Pronunciation and other accents of English. (Some have called this "levelling", but this is rarely used because it may be confused with dialect levelling.) For example, chaos, pronounced pronounced as /[ˈkeɪɒs]/ without smoothing, becomes pronounced as /[ˈkeːɒs]/ with smoothing. Smoothing applies particularly readily to pronounced as //aɪ// and pronounced as //aʊ// when preceding pronounced as //ə//, hence pronounced as /[faːə]/ for fire and pronounced as /[taːə]/ for tower, or with the syllabicity loss of pronounced as //ə//, pronounced as /[faə̯, taə̯]/. The centring diphthong pronounced as /[aə̯]/ deriving from smoothing and syllabicity loss may further undergo monophthongization, realizing fire and tower as pronounced as /[faː, taː]/ or pronounced as /[fɑː, tɑː]/, similar or identical to far, tar; unlike smoothing, this type of monophthongization (which Wells terms "monophthonging") does not require a following vowel.[4]
Smoothing can occur across word boundaries in the same conditions (closing diphthong + vowel), as in pronounced as /[weː aʊt]/ way out, pronounced as /[ðeː iːt]/ they eat, pronounced as /[ɡəː ɒf]/ go off.[5]
Vedic Sanskrit diphthongs pronounced as //ɐɪ// and pronounced as //ɐʊ// later monophthongize to pronounced as //eː// and pronounced as //oː// respectively in Classical Sanskrit, but these may remain as diphthongs under sandhi rules.[6]
In Hindustani, the pure vowels pronounced as //ɛː// and pronounced as //ɔː// are written with the letters for the diphthongs ai and au in Devanagari and related alphabets. The vowel sequences pronounced as //aːɪ// and pronounced as //aːʊ// exist in Hindi, but are written as āi and āu, with long initial vowels.
The so-called early frühneuhochdeutsche Monophthongierung (monophthongization in the earliest stages of New High German) is particularly important in today's Standard German.[7] It changed the diphthongs ie pronounced as /[iə]/, uo pronounced as /[uə]/ and üe pronounced as /[yə]/ to respectively ie pronounced as /[iː]/, u pronounced as /[uː]/ and ü pronounced as /[yː]/:
Before 11th century > nowadays:
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 pronounced as //ei ou// monophthongized to pronounced as //eː oː// around the 5th century BC, and the diphthong pronounced as //ai// monophthongized to pronounced as //eː// in the Koine Greek period. For more information, see and Koine Greek phonology.
French underwent monophthongization and so the digraph (ai), which formerly represented a diphthong, represents the sound pronounced as //ɛ// or pronounced as //e// in Modern French. Similarly, the digraph (au) and trigraph (eau) represent the monophthong pronounced as //o// due to the same process.
Korean underwent monophthongization two times─18th century, and 20th century. Their common point is that all of the monophthongized vowels were falling diphthongs. In 18th century, pronounced as //ɐi əi// monophthongized to pronounced as //ɛ e//. Similarly, in 20th century pronounced as //oi ui// monophthongized to pronounced as //ø y//.