Inphonetics andphonology, asemivowel,glide orsemiconsonant is a sound that is phonetically similar to avowel sound but functions as thesyllable boundary, rather than as thenucleus of a syllable.[1] Examples of semivowels in English arey andw inyes andwest, respectively. Written/jw/ inIPA,y andw are near to the vowelsee andoo inseen andmoon, written/iːuː/ in IPA. The termglide may alternatively refer to any type of transitional sound, not necessarily a semivowel.[2]
Semivowels form a subclass ofapproximants.[3][4] Although "semivowel" and "approximant" are sometimes treated as synonymous,[5] most authors use the term "semivowel" for a more restricted set; there is no universally agreed-upon definition, and the exact details may vary from author to author. For example,Ladefoged & Maddieson (1996) do not consider thelabiodental approximant[ʋ] to be a semivowel.[6]
In theInternational Phonetic Alphabet, the diacritic attached to non-syllabic vowel letters is aninverted breve placed below the symbol representing the vowel:U+032F ◌̯COMBINING INVERTED BREVE BELOW. When there is no room for the inverted breve under a symbol, it may be written above, usingU+0311 ◌̑COMBINING INVERTED BREVE. Before 1989, non-syllabicity was represented byU+0306 ◌̆COMBINING BREVE, which now stands forextra-shortness.
Additionally, there are dedicated symbols for four semivowels that correspond to the four closecardinal vowel sounds:[4]
| Semivowel (non-syllabic) | Vowel (syllabic) |
|---|---|
| [j] (palatal approximant) | [i] (close front unrounded vowel) |
| [ɥ] (labio-palatal approximant) | [y] (close front rounded vowel) |
| [ɰ] (velar approximant) | [ɯ] (close back unrounded vowel) |
| [w] (labiovelar approximant) | [u] (close back rounded vowel) |
In addition, some authors[6][7] consider therhotic approximants[ɹ],[ɻ] to be semivowels corresponding toR-colored vowels such as[ɚ]. An unrounded central semivowel,[j̈] (or[j˗]), equivalent to[ɨ], is uncommon, though rounded[ẅ] (or[w̟]), equivalent to[ʉ], is found inSwedish andNorwegian.
Semivowels, by definition, contrast with vowels by being non-syllabic. In addition, they are usually shorter than vowels.[3] In languages such asAmharic,Yoruba, andZuni, semivowels are produced with a narrower constriction in the vocal tract than their corresponding vowels.[6] Nevertheless, semivowels may be phonemically equivalent with vowels. For example, the English wordfly can be considered either as anopen syllable ending in adiphthong[flaɪ̯] or as aclosed syllable ending in a consonant[flaj].[8]
It is unusual for a language to contrast a semivowel and a diphthong containing an equivalent vowel,[citation needed] butRomanian contrasts the diphthong/e̯a/ with/ja/, a perceptually similar approximant-vowel sequence. The diphthong is analyzed as a single segment, and the approximant-vowel sequence is analyzed as two separate segments.
In addition to phonological justifications for the distinction (such as the diphthong alternating with/e/ in singular-plural pairs), there are phonetic differences between the pair:[9]
Although a phonological parallel exists between/o̯a/ and/wa/, the production and perception of phonetic contrasts between the two is much weaker, likely because of lower lexical load for/wa/, which is limited largely to loanwords fromFrench, and speakers' difficulty in maintaining contrasts between two back rounded semivowels in comparison to front ones.[10]
According to the standard definitions, semivowels (such as[j]) contrast withfricatives (such as[ʝ]) in that fricatives produce turbulence, but semivowels do not. In discussingSpanish, Martínez Celdrán suggests setting up a third category of "spirant approximant", contrasting both with semivowel approximants and with fricatives.[11] Though the spirant approximant is more constricted (having a lowerF2 amplitude), longer, and unspecified for rounding (viuda[ˈbjuða] 'widow' vs.ayuda[aˈʝʷuða] 'help'),[12] the distributional overlap is limited. The spirant approximant can only appear in the syllable onset (including word-initially, where the semivowel never appears). The two overlap in distribution after/l/ and/n/:enyesar[ẽɲɟʝeˈsaɾ] ('to plaster')aniego[ãˈnjeɣo] ('flood')[13] and although there is dialectal and idiolectal variation, speakers may also exhibit other near-minimal pairs likeabyecto ('abject') vs.abierto ('opened').[14] One potential minimal pair (depending on dialect) isya visto[(ɟ)ʝaˈβisto] ('already seen') vs.y ha visto[jaˈβisto] ('and he has seen').[15]Again, it is not present in all dialects. Other dialects differ in either merging the two or enhancing the contrast by moving the former to anotherplace of articulation ([ʒ]), like inRioplatense Spanish.
