In phonetics, retroflex consonants are consonant sounds used in some languages. (They are sometimes referred to as cerebral consonants, especially in indology.) The tongue is placed behind the alveolar ridge, and may even be curled back to touch the palate: that is, they are articulated in the postalveolar to palatal region of the mouth.
Retroflex consonants, like other coronals, come in several varieties, depending on the shape of the tongue. The tongue may be flat, with the blade of the tongue (the top surface of the tongue near the tip) touching the roof of the mouth, as in Polish cz, sz, ż (rz), dż and Mandarin zh, ch, sh, r. This is termed laminal (laminal retroflex). Or they may be pronounced with the tip of the tongue, as in Hindi. This is termed apical (apical retroflex). Finally, the tongue may be curled back so that the underside touches the alveolar or pre-palatal region, as in many of the Dravidian languages. This is termed sub-apical (sub-apical retroflex).
The consonants commonly called postalveolar, or more precisely palato-alveolar, such as English sh and ch, as well as the alveolo-palatals, such as Mandarin q, j, x, are also pronounced in the postalveolar region. However, they differ from retroflex consonants in having an additional secondary articulation of palatalization. The consonants commonly called palatal are pronounced in the palatal region like the sub-apical retroflexes, but they touch the palate with the back of the tongue, not the tip. (That is, they are dorsal, or more precisely dorso-palatal, rather than coronal consonants.)
In other words, retroflex consonants include various types of coronal consonants articulated behind the alveolar ridge which do not have the secondary articulation of palatalization.
Retroflex consonants are concentrated in the Indo-Aryan languages and the Dravidian languages of the Indian subcontinent, where they occur as an areal feature apparently inherited from Dravidian (they do not exist in Proto-Indo-Iranian). They also occur in some other Asian languages such as Mandarin Chinese, Javanese and Vietnamese. The other major concentration is in the indigenous languages of Australia and the Western Pacific (notably New Caledonia). Here, most languages have retroflex plosives, nasal and approximants.
There are several retroflex consonants not yet recognized by the IPA. For example, the Iwaidja language of northern Australia has a retroflex lateral flap [ɺ̡] as well as a retroflex tap [ɽ] and retroflex lateral approximant [ɭ]; and the Dravidian language Toda has a sub-apical retroflex lateral fricative [ɬ̡] and a retroflexed trill [ɽ͡r]. Because of the regularity of deriving retroflex symbols from their alveolar counterparts, people will occasionally use a font editor to create the appropriate symbols for such sounds. (Here they were written with diacritics.) The Ngad'a language of Flores has been reported to have a retroflex implosive [ᶑ], but in this case the expected symbol is coincidentally supported by Unicode. Sub-apical retroflex clicks occur in Central Juu and in Damin.
Retroflex consonants identified by the International Phonetic Alphabet are:
|style="border:1px solid black"||retroflex nasal||Swedish||Vänern||[vɛː.neɳ]||Vänern|
|style="border:1px solid black"||voiceless retroflex plosive||Hindi||टापू (ṭāpū)||[ʈɑpu]||island|
|style="border:1px solid black"||voiced retroflex plosive||Swedish||nord||[nuːɖ]||north|
|style="border:1px solid black"||voiceless retroflex fricative||Mandarin||上海 (Shànghǎi)||[ʂɑ̂ŋ.xàɪ]||Shanghai|
|style="border:1px solid black"||voiced retroflex fricative||Russian|
|style="border:1px solid black"||retroflex approximant||Tamil||தமிழ் (Tamil)||[t̪ɐmɨɻ]||Tamil|
|style="border:1px solid black"||lateral retroflex approximant||Swedish||Karlstad||[kʰɑːɭ.sta]||Karlstad|
|style="border:1px solid black"||retroflex flap||Hausa||shaara||[ʃáːɽa]||sweeping|
|ɺ̡||retroflex lateral flap||Pashto||ﻛړو||[kɺ̡o]||to do|
|ǃ˞||(voiced) retroflex click||Central Juu||—||[ɡǃ˞ú]||water|
Note: In the International Phonetic Alphabet, the symbols for retroflex consonants are typically the same as for the alveolar consonants, but with the addition of a right-facing hook to the bottom of the symbol. Some linguists restrict these symbols for the "true" retroflex consonants with sub-apical palatal articulation, and use the alveolar symbols with the obsolete IPA underdot symbol for an apical post-alveolar articulation: . Another solution, more in keeping with the official IPA, would be to use the rhotic diacritic for the apical retroflexes: . Laminal retroflexes, as in Polish and Russian, are often transcribed with a retraction diacritic, as [s̱], etc. Otherwise they are typically but inaccurately transcribed as if they were palato-alveolar, as *[ʃ], etc.