Relative articulation

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. 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. For letters with descenders, diacritics above or obsolete U+02D6 ˖ MODIFIER LETTER PLUS SIGN and U+02D7 ˗ MODIFIER LETTER MINUS SIGN may instead be used after the letter, as in [ɡ˖] and [y˗].

Both vowels and consonants may be fronted or backed. In verbal description, the prefix pre- may be used to indicate fronting, especially in the terms prepalatal and prevelar. Otherwise phrases like "fronted u" may be used. For retraction, either the prefix post- may be used to indicate retraction, as above, or phrases like "retracted i" may be used.

In most dialects of English, the back vowel /u/ is farther forward than what is normally indicated by the IPA letter ‹u›. This fronting may be shown explicitly, especially within a narrow transcription: [u̟]. Whether this is as far front as the central vowel [ʉ], or somewhere between [u] and [ʉ], may need to be clarified verbally, or on a vowel diagram.

The difference between a fronted and non-fronted consonant can be heard in the English words key [k̟ʰi] and coo [kʰu], where the /k/ in key is fronted under the influence of the front vowel /i/. In English, the plosive in the affricate /tʃ/, as in the word church, is farther back than an alveolar /t/ due to assimilation with the postalveolar fricative /ʃ/. In narrow transcription, /tʃ/ may be transcribed [t̠ʃʰ]. In English, the /d/ in the phrase "I need that" is farther front than normal due to assimilation with the interdental consonant /ð/, and may be transcribed as [aɪ̯ ˈniːd̟ ðæt].

Languages may have phonemes that are farther back than the nearest IPA symbol. For example, Polish sz is a postalveolar sibilant. While this is often transcribed as [ʃ], it is not domed (partially palatalized) the way a prototypical [ʃ] is. A more precise transcription is therefore [s̠]. Similarly, the velar consonants in Kwakiutl are actually postvelar; that is, pronounced farther back than a prototypical velar, between velar [k] and uvular [q], and is thus transcribed [k̠].

Officially, the IPA symbol [a] stands for the open front unrounded vowel. However, in most languages where it is used, [a] actually stands for the central, rather than the front vowel. If precision is desired, this may also be indicated with the minus sign [a̠], although a number of other transcriptions are also possible.