Alveolo-palatal consonants

In phonetics, alveolo-palatal (or alveopalatal) consonants, sometimes synonymous with pre-palatal consonants, are intermediate in articulation between the coronal and dorsal consonants, or which have simultaneous alveolar and palatal articulation. In the official IPA chart, alveolo-palatals would appear between the retroflex and palatal consonants but for "lack of space". Ladefoged and Maddieson characterize the alveolo-palatals as palatalized postalveolars (palatalized palato-alveolars), articulated with the blade of the tongue behind the alveolar ridge and the body of the tongue raised toward the palate, whereas Esling describes them as advanced palatals (pre-palatals), the furthest front of the dorsal consonants, articulated with the body of the tongue approaching the alveolar ridge. These descriptions are essentially equivalent, since the contact includes both the blade and body (but not the tip) of the tongue (see schematic at right). They are front enough that the fricatives and affricates are sibilants, the only sibilants among the dorsal consonants.

The alveolo-palatal sibilants are often used in varieties of Chinese such as Mandarin, Hakka, and Wu, as well as other East Asian languages such as Japanese and Korean. Alveolo-palatal sibilants are also a feature of many Slavic languages, such as Polish, Russian, and Serbo-Croatian, and of Northwest Caucasian languages, such as Abkhaz and Ubykh. The alveolo-palatal consonants included in the International Phonetic Alphabet are:

...
Wikipedia