Semivowel

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In phonetics and phonology, a semivowel, glide or semiconsonant is a sound that is phonetically similar to a vowel sound but functions as the syllable boundary, rather than as the nucleus of a syllable.^[1] Examples of semivowels in English are the consonants y and w in yes and west, respectively. Written /j w/ in IPA, y and w are near to the vowels ee and oo in seen and moon, written /iː uː/ in IPA. The term glide may alternatively refer to any type of transitional sound, not necessarily a semivowel.^[2]

Classification

Semivowels form a subclass of approximants.^[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 the labiodental approximant [ʋ] to be a semivowel.^[6]

In the International Phonetic Alphabet, the diacritic attached to non-syllabic vowel letters is an inverted 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, using U+0311 ◌̑ COMBINING INVERTED BREVE. Before 1989, non-syllabicity was represented by U+0306 ◌̆ COMBINING BREVE, which now stands for extra-shortness.

Additionally, there are dedicated symbols for four semivowels that correspond to the four close cardinal 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 the rhotic approximants [ɹ], [ɻ] to be semivowels corresponding to R-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 in Swedish and Norwegian.

Contrast with vowels

Semivowels, by definition, contrast with vowels by being non-syllabic. In addition, they are usually shorter than vowels.^[3] In languages such as Amharic, Yoruba, and Zuni, 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 word fly can be considered either as an open syllable ending in a diphthong [flaɪ̯] or as a closed 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]} but Romanian 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]

/ja/ has a greater duration than /e̯a/
The transition between the two elements is longer and faster for /ja/ than /e̯a/ with the former having a higher F2 onset (greater constriction of the articulators).

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 from French, and speakers' difficulty in maintaining contrasts between two back rounded semivowels in comparison to front ones.^[10]

Contrast with fricatives/spirant approximants

According to the standard definitions, semivowels (such as [j]) contrast with fricatives (such as [ʝ]) in that fricatives produce turbulence, but semivowels do not. In discussing Spanish, 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 lower F2 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 like abyecto ('abject') vs. abierto ('opened').^[14] One potential minimal pair (depending on dialect) is ya 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 another place of articulation ([ʒ]), like in Rioplatense Spanish.

References

^ Ladefoged & Maddieson (1996), p. 322.
^ Crystal (2008), p. 211.
^ ^a ^b Crystal (2008), pp. 431–2.
^ ^a ^b Martínez Celdrán (2004), p. 9.
^ Meyer (2005), p. 101.
^ ^a ^b ^c Ladefoged & Maddieson (1996), p. 323.
^ Martínez Celdrán (2004), p. 8.
^ Cohen (1971), p. 51.
^ Chitoran (2002), pp. 212–214.
^ Chitoran (2002), p. 221.
^ Martínez Celdrán (2004), p. 6.
^ Martínez Celdrán (2004), p. 208.
^ Trager (1942), p. 222.
^ Saporta (1956), p. 288.
^ Bowen & Stockwell (1955), p. 236.

Sources

Bowen, J. Donald; Stockwell, Robert P. (1955), "The Phonemic Interpretation of Semivowels in Spanish", Language, 31 (2): 236–240, doi:10.2307/411039, JSTOR 411039
Chitoran, Ioana (2002), "A perception-production study of Romanian diphthongs and glide-vowel sequences" (PDF), Journal of the International Phonetic Association, 32 (2): 203–222, CiteSeerX 10.1.1.116.1413, doi:10.1017/S0025100302001044, S2CID 10104718
Crystal, David (2008), A Dictionary of Linguistics and Phonetics (6th ed.), Blackwell, ISBN 978-1-4051-5297-6
Cohen, Antonie [in Dutch] (1971), The phonemes of English: a phonemic study of the vowels and consonants of standard English (third ed.), Springer, ISBN 978-90-247-0639-6
Ladefoged, Peter; Maddieson, Ian (1996). The Sounds of the World's Languages. Oxford: Blackwell. ISBN 0-631-19815-6.
Martínez Celdrán, Eugenio (2004), "Problems in the Classification of Approximants" (PDF), Journal of the International Phonetic Association, 34 (2): 201–210, doi:10.1017/S0025100304001732, S2CID 144568679, archived from the original (PDF) on 2010-07-11, retrieved 2015-02-14
Meyer, Paul Georg (2005), Synchronic English Linguistics: An Introduction (third ed.), Tübingen: Gunter Narr Verlag, ISBN 978-3-8233-6191-6
Saporta, Sol (1956), "A Note on Spanish Semivowels", Language, 32 (2): 287–290, doi:10.2307/411006, JSTOR 411006
Trager, George (1942), "The Phonemic Treatment of Semivowels", Language, 18 (3): 220–223, doi:10.2307/409556, JSTOR 409556