Vowel height in the context of "Vowel harmony"

The open-mid back rounded vowel, or low-mid back rounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɔ⟩. The IPA symbol is a turned letter c and both the symbol and the sound are commonly called "open-o". The name open-o represents the sound, in that it is like the sound represented by ⟨o⟩, the close-mid back rounded vowel, except it is more open. It also represents the symbol, which can be remembered as an o which has been "opened" by removing part of the closed circular shape.

In English, the symbol ⟨ɔ⟩ (or ⟨ɔː⟩) is typically associated with the vowel in "thought", but in Received Pronunciation ("RP", standard British English), Australian English, New Zealand English and South African English that vowel is produced with considerably stronger lip rounding and higher tongue position than that of cardinal [ɔ], i.e. as close-mid [oː] or somewhat lower. Open-mid [ɔː] or even open [ɒː] realizations are found in North American English (where this vowel is often indistinguishable from the open back unrounded vowel in "bra") and Scottish English as well as Hiberno-English, Northern England English and Welsh English, though in the last three accent groups closer, [oː]-like realizations are also found. In RP, the open-mid realization of /ɔː/ has been obsolete since the 1930s. Pronouncing that vowel as such is subject to correction for non-native speakers aiming at RP.

In phonetics, vowel roundedness is the amount of rounding in the lips during the articulation of a vowel. It is labialization of a vowel. When a rounded vowel is pronounced, the lips form a circular opening, and unrounded vowels are pronounced with the lips relaxed. In most languages, front vowels tend to be unrounded, and back vowels tend to be rounded. However, some languages, such as French, German and Icelandic, distinguish rounded and unrounded front vowels of the same height (degree of openness), and others, like Vietnamese and Turkish, distinguishes rounded and unrounded back vowels of the same height. Alekano is unusual in having only unrounded vowels.

In the International Phonetic Alphabet vowel chart, rounded vowels are the ones that appear on the right in each pair of vowels. There are also diacritics, U+0339 ◌̹ COMBINING RIGHT HALF RING BELOW and U+031C ◌̜ COMBINING LEFT HALF RING BELOW, to indicate greater and lesser degrees of rounding, respectively.Thus [o̜] has less rounding than cardinal [o], and [o̹] has more (closer to the rounding of cardinal [u]). These diacritics can also be used with unrounded vowels: [ɛ̜] is more spread than cardinal [ɛ], and [ɯ̹] is less spread than cardinal [ɯ].

A vowel diagram or vowel chart is a schematic arrangement of vowels within a phonetic system. Vowels do not differ in place, manner, or voicing in the same way that consonants do. Instead, vowels are distinguished primarily based on their height (vertical tongue position), backness (horizontal tongue position), and roundness (lip articulation). Depending on the particular language being discussed, a vowel diagram can take the form of a triangle or a quadrilateral.

The vowel diagram of the International Phonetic Alphabet is based on the cardinal vowel system, displayed in the form of a trapezium. In the diagram, convenient reference points are provided for specifying tongue position. The position of the highest point of the arch of the tongue is considered to be the point of articulation of the vowel.