Semivowel
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Semivowels— also known as glides, especially in older literature—are non-syllabic vowels that form diphthongs with full syllabic vowels. That is, they are vowel-like sounds that do not form the nucleus of a syllable or mora; they are not the most prominent part of the syllable. They are normally written by adding the IPA non-syllabicity mark [  ̯ ] to a vowel letter, but often for simplicity the vowel letter alone is written.

Semivowels may contrast with approximants, which are similar to but closer than vowels or semivowels and behave as consonants.

To illustrate, the English word wow may be transcribed as [waʊ̯] (often approximated as [waʊ]). Even though both the [w] and the [ʊ̯] are similar sounds to the vowel [u], the transcription [waʊ̯] indicates that the initial segment is considered to be a consonant by the transcriber, while the final segment is considered to form a diphthong with the preceding vowel. The approximant w is more constricted and therefore more consonant-like than the semivowel [ʊ̯] or the vowel [u].

Because they are so similar phonetically, the concepts of semivowel and approximant are often used interchangeably. In this conflated usage, semivowels are defined as those approximants that correspond phonetically to specific close vowels. These are j, corresponding to i; w for u; ɥ for y; and ɰ for ɯ. In American English, there is also rhotic [ɹ] for [ɝ]. (See approximant for details.) However, languages such as Nepali, Romanian and Samoan have additional semivowels such as [e̯] and [o̯] that correspond to mid vowels, and which other than being non-syllabic are not at all like consonants.

Examples

In languages such as Japanese and Hawaiian, every vocalic segment constitutes a separate syllable or mora. That is, at least in careful speech, there are no diphthongs. For example, the Japanese word hai 'yes' is pronounced [ha.i], and aoi 'be blue/green' is [a.o.i]. (The sounds /j/ and /w/ behave as consonants in these languages.)

Close semivowels

• English eye [ɑɪ̯]
• English cow [kaʊ̯]
• Dutch ui "onion" [œʏ̯]

Close vs. mid semivowels

• Samoan ’ai "probably" [ʔai̯]
• Samoan ’ae "but" [ʔae̯]
• Samoan ’auro "gold" [ʔau̯ɾo]
• Samoan ao "a cloud" [ao̯]

Semivowel schwas

Non-rhotic dialects of English have a non-syllabic schwa immediately after the vowel nucleus, as in RP [ˈfɛə̯] fair. Many dialects of German do something similar, as in Tor [ˈtʰoːɐ̯] 'gate' and Würde [ˈvʏɐ̯də] 'dignity'. In rhotic dialects of English, the final r may be considered a rhotic semivowel rather than a consonant; the decision whether to transcribe fair as [ˈfɛɚ̯] or [ˈfɛɹ] is similar to the choice of [ˈbaɪ̯] vs. [ˈbaj] for buy (see below).

Transcription

Diphthongs are variously transcribed in English. The simplest method, typographically, is to write eye as [aj] and cow as [kaw]. However, phoneticians often object that the final segments of these words do not have the constriction that characterizes the consonants [j] and [w] in yes [jɛs] and wall [wɔɫ], but rather are purely vocalic, and that therefore the symbols <j> and <w> are inappropriate. In languages that contrast [ao̯] with [au̯], such as Samoan, the symbol <w> obviously cannot be used for both. Transcribing them with vowel symbols not only enables that contrast, but it allows a more precise transcription of other diphthongs. For example, the diphthong in English bay is often transcribed with a near-high semivowel, [beɪ̯], as being more accurate than a fully high semivowel, [bei̯].

See also

• Diphthong
• List of phonetics topics
• Syllabic consonant
• Vowel cluster
• Hiatus (linguistics)

References

Bibliography

• Martínez-Celdrán, Eugenio; Ana Ma. Fernández-Planas & Josefina Carrera-Sabaté (2003), "Castilian Spanish", Journal of the International Phonetic Association 33 (2): 255-259

Further reading

• Martínez-Celdrán, Eugenio (2004), "Problems in the classification of approximants", Journal of the International Phonetic Association 34 (2): 201-210