More rounded

Advanced, retracted
◌̟ ◌˖
◌̠ ◌˗

Raised and lowered
◌̝ ◌˔
◌̞ ◌˕

Centralized
◌̈

Mid-centralized
◌̽

More or less rounded
◌̹
◌̜

In phonetics and phonology, relative articulation is description of the manner and place of articulation of a speech sound relative to some reference point. Typically, the comparison is made with a default, unmarked articulation of the same phoneme in a neutral sound environment. For example, the English velar consonant /k/ is fronted before the vowel /iː/ (as in keep) compared to articulation of /k/ before other vowels (as in cool). This fronting is called palatalization.

The relative position of a sound may be described as advanced (fronted), retracted (backed), raised, lowered, centralized, or mid-centralized. The latter two terms are only used with vowels, and are marked in the International Phonetic Alphabet with diacritics over the vowel letter. The others are used with both consonants and vowels, and are marked with iconic diacritics under the letter. Another dimension of relative articulation that has IPA diacritics is the degree of roundedness, more rounded and less rounded.

An advanced or fronted sound is one that is pronounced farther to the front of the vocal tract than some reference point. The diacritic for this in the IPA is the subscript plus, U+031F ̟ COMBINING PLUS SIGN BELOW (HTML ̟). Conversely, a retracted or backed sound is one that is pronounced farther to the back of the vocal tract, and its IPA diacritic is the subscript minus U+0320 ̠ COMBINING MINUS SIGN BELOW (HTML ̠). When there is no room for the tack under a letter, it may be written after, using: U+02D6 ˖ MODIFIER LETTER PLUS SIGN as in [ɡ˖], or U+02D7 ˗ MODIFIER LETTER MINUS SIGN as in [y˗].

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Wikipedia