Mid vowel

A mid vowel is a vowel sound used in some spoken languages. The defining characteristic of a mid vowel is that the tongue is positioned mid-way between an open vowel and a close vowel. The only mid vowel with a dedicated symbol in the International Phonetic Alphabet is the mid central vowel without specified rounding.

There also are mid vowels that do not have dedicated symbols in the IPA:
 * mid front unrounded vowel or  (commonly written, i.e. as if it were close-mid)
 * mid front rounded vowel or  (commonly written, i.e. as if it were close-mid)
 * mid near-front unrounded vowel or
 * mid near-front rounded vowel or
 * mid central unrounded vowel or  (most often written )
 * mid central rounded vowel or  (most often written, i.e. as if it were close-mid)
 * mid near-back unrounded vowel or
 * mid near-back rounded vowel or
 * mid back unrounded vowel or  (commonly written, i.e. as if it were close-mid)
 * mid back rounded vowel or  (commonly written, i.e. as if it were close-mid)

The IPA divides the vowel space into thirds, with the close-mid vowels such as or  and the open-mid vowels such as  or  equidistant in formant space between open  and close  or. Thus a true mid front vowel could be transcribed as either a lowered or a raised.

Few languages contrast all three heights of mid vowel, because it is rare for a language to distinguish more than four heights of true front or back vowels. One, the Amstetten dialect of Austro-Bavarian, contrasts four heights of front unrounded, front rounded, and back vowels in addition to having an open central vowel. These have been transcribed with the available IPA symbols, , , and.

However, the vowels transcribed are one-third the distance between open  and close, precisely the IPA definition of open-mid vowels. Thus Amstetten Bavarian may be an example of a language that contrasts mid vowels with both open-mid and close-mid vowels.

The Kensiu language spoken in Malaysia and Thailand is highly unusual in that it contrasts true-mid vowels with close-mid and open-mid vowels without differences in other parameters such as backness or roundedness.