Vertical vowel system

Vertical vowel system refers to a system of vowels in a language which uses just one dimension to phonemically distinguish vowels. Theoretically, rounding, frontness and backness, and vowel height could be used in one-dimensional vowel systems; however, vertical refers to the usage of vowel height as the sole distinguishing feature.

Vertical vowel systems need not be phonetically vertical. Wichita, for instance, possesses a vertical vowel system. However, two of the vowels it uses (e and i) are phonetically fronted, and the other (a) is phonetically backed. o is also heard phonetically, but is a contraction of [short vowel + w + short vowel].

Zero-dimensional vowel systems have been postulated for some Abkhaz dialects, and for Kabardian; however, it is generally accepted that these analyses are flawed.

Vertical vowel systems have been noted for the following languages:

• Northwest Caucasian family
  • Abkhaz (distinguishes a and i)
  • Adyghe (distinguishes a, e and i)
  • Kabardian (distinguishes a, i and possibly e)
  • Ubykh (distinguishes a and i)
• Caddoan family
  • Wichita (distinguishes a, e and i)