Semivowel

In phonetics and phonology, a semivowel or glide, also known as a non-syllabic vocoid, 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. 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.

Classification

Semivowels form a subclass of approximants.^[2][3] Although "semivowel" and "approximant" are sometimes treated as synonymous,^[4] most authors agree that not all approximants are semivowels although 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^[5] while Martínez Celdrán (2004) proposes that it should be considered one.^[6]

In the International Phonetic Alphabet, the diacritic attached to non-syllabic vowel letters is U+032F ̯ COMBINING INVERTED BREVE BELOW. When there is no room for the tack under a letter, it may be written above, using U+0311 ̑ COMBINING INVERTED BREVE. Sometimes,^[7] the 'extra-short' diacritic (U+0306 ̆ COMBINING BREVE) is used instead, which is not a completely correct transcription.

Additionally, there are dedicated symbols for four semivowels that correspond to the four close cardinal vowel sounds:^[3]

The pharyngeal approximant [ʕ̞] is also equivalent to the semivowel articulation of the open back unrounded vowel [ɑ̯].^[5]

In addition, some authors^[5][6] consider the rhotic approximants [y], [ɻ ] to be semivowels corresponding to R-colored vowels such as [ɚ]. As mentioned above, the labiodental approximant [ʋ] is considered a semivowel in some treatments. An unrounded central semivowel, [ ȷ̈ ] (also written ⟨ɉ⟩), 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.^[2] In languages as diverse as Amharic, Yoruba, and Zuni, semivowels are produced with a narrower constriction in the vocal tract than their corresponding vowels.^[5] 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, 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 analysed 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 a difficulty in maintaining contrasts between two back rounded glides 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 [ãnjeɣo] ('flood')^[13] and although there is dialectal and ideolectal 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] ('I have 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 in enhancing the contrast by moving the former to another place of articulation ([ʒ]).

See also

• Diphthong
• List of phonetics topics
• Syllabic consonant
• Hiatus (linguistics)
• Voiced labio-velar approximant

References

Bibliography

Further reading