Classification
Semivowels form a subclass of approximants. Although "semivowel" and "approximant" are sometimes treated as synonymous, most authors agree that not all approximants are semivowels, although the exact details may vary from author to author. For example, Ladefoged & Maddieson (1996) don't consider the labiodental approximant to be a semivowel, while Martínez-Celdrán (:2004) proposes that it should be considered one.
In the International Phonetic Alphabet, the diacritic attached to non-syllabic vowel letters is ⟨ ̯ ⟩ (U+032F ̯ combining inverted breve below). Additionally, there are dedicated letters for four semivowels that correspond to the four close cardinal vowel sounds:
| Semivowel (non-syllabic) | Vowel (syllabic) |
|---|---|
| (palatal approximant) | (close front unrounded vowel) |
| (labio-palatal approximant) | (close front rounded vowel) |
| (velar approximant) | (close back unrounded vowel) |
| (labiovelar approximant) | (close back rounded vowel) |
The pharyngeal approximant is also equivalent to the semivowel articulation of the open back unrounded vowel .
In addition, some authors consider the rhotic approximants, to be semivowels corresponding to R-colored vowels such as . As mentioned above, the labiodental approximant is considered a semivowel in some treatments. A central semivowel, (also written ), is uncommon. The semivowel corresponding to the close mid front unrounded vowel, here provisionally defined as "semipalatal semilateral" approximant, is currently attested only in some varieties of Venetian as an allophone of the lateral consonant /l/ and can also be reduced to zero.
Read more about this topic: Semivowel