Postalveolar consonant

There are many types of postalveolar sounds—especially among the sibilants. The three primary types are palato-alveolar (such as , weakly palatalized; also alveopalatal), alveolo-palatal (such as , strongly palatalized), and retroflex (such as , unpalatalized). The palato-alveolar and alveolo-palatal subtypes are commonly counted as "palatals" in phonology since they rarely contrast with true palatal consonants.

Postalveolar sibilants

For most sounds involving the tongue, the place of articulation can be sufficiently identified just by specifying the point of contact on the upper part of the mouth (for example, velar consonants involve contact on the soft palate and dental consonants involve the teeth), along with any secondary articulation such as palatalization (raising of the tongue body) or labialization (lip rounding).

However, among sibilants, particularly postalveolar sibilants, there are slight differences in the shape of the tongue and the point of contact on the tongue itself, which correspond to large differences in the resulting sound. For example, the alveolar fricative and the three postalveolar fricatives differ noticeably both in pitch and sharpness; the order corresponds to progressively lower-pitched and duller (less "hissy" or piercing) sounds. ( is the highest-pitched and most piercing, which is the reason that hissing sounds like "Sssst!" or "Psssst!" are typically used to attract someone's attention). As a result, it is necessary to specify many additional subtypes.

Tongue shape

The main distinction is the shape of the tongue, which corresponds to differing degrees of palatalization (raising of the body of the tongue). From least to most palatalized, they are retroflex (such as , unpalatalized); palato-alveolar (such as , weakly palatalized); and alveolo-palatal (such as , strongly palatalized). The increasing palatalization corresponds to progressively higher-pitched and sharper-sounding consonants.

Less technically, the retroflex consonant sounds somewhat like a mixture between the regular English of "ship" and the "h" at the beginning of "heard", especially when it is pronounced forcefully and with a strong American "r". The alveolo-palatal consonant sounds like a strongly palatalized version of , somewhat like "nourish you".

The following table shows the three types of postalveolar sibilant fricatives defined in the IPA:

Active articulator

A second variable is whether the contact occurs with the very tip of the tongue (an apical articulation ), with the surface just above the tip, the blade of the tongue (a laminal articulation ), or with the underside of the tip (a subapical articulation). Apical and subapical articulations are always "tongue-up", with the tip of the tongue above the teeth, and laminal articulations are often "tongue-down", with the tip of the tongue behind the lower teeth.

The upward curvature of the tongue tip to make apical or subapical contact renders palatalization more difficult so domed (palato-alveolar) consonants are not attested with subapical articulation and fully palatalized (such as alveolo-palatal) sounds occur only with laminal articulation. The apical–laminal distinction among palato-alveolar sounds makes little (although presumably non-zero) perceptible difference; both articulations, in fact, occur among English-speakers.

As a result, the differing points of tongue contact (laminal, apical and subapical) are significant largely for retroflex sounds. Retroflex sounds can also occur outside of the postalveolar region, ranging from as far back as the hard palate to as far forward as the alveolar region behind the teeth. Subapical retroflex sounds are often palatal (and vice versa), which occur particularly in the Dravidian languages.

Tongue-down distinction

There is an additional distinction that can be made among tongue-down laminal sounds, depending on exactly where behind the lower teeth the tongue tip is placed. A bit behind the lower teeth is a hollow area (or pit) in the lower surface of the mouth. When the tongue tip rests in the hollowed area, there is an empty space below the tongue (a sublingual or postdental cavity), which results in a relatively more "hushing" sound. When the tip of the tongue rests against the lower teeth, there is no sublingual cavity, resulting in a more "hissing" sound. Generally, the tongue-down postalveolar consonants have the tongue tip on the hollowed area (with a sublingual cavity), whereas for the tongue-down alveolar consonants, the tongue tip rests against the teeth (no sublingual cavity), which accentuates the hissing vs. hushing distinction of these sounds.

However, the palato-alveolar sibilants in Northwest Caucasian languages such as the extinct Ubykh have the tongue tip resting directly against the lower teeth rather than in the hollowed area, resulting in the absence of a sublingual cavity. Ladefoged & Maddieson (1996) term this a "closed laminal postalveolar" articulation, which gives the sounds a quality that J. C. Catford describes as "hissing-hushing" sounds. Catford transcribes them as ⟨⟩, but this is not IPA notation; the obsolete IPA letters ⟨⟩ have occasionally been resurrected for these sounds, and the original 1900 IPA chart included the symbols ⟨⟩ for them (the 1904 English-version supplemental material referred to them as "Circassian dental hiss[es]").

A laminal "closed" articulation could theoretically be made with alveolo-palatal sibilants and a laminal "non-closed" articulation with alveolar sibilants, but no language appears to do so. In addition, no language seems to have a minimal contrast between two sounds based only on the "closed"–"non-closed" variation, with no concomitant articulatory distinctions (for all languages, including the Northwest Caucasian languages, if the language has two laminal sibilants, one of which is "closed" and the other is "non-closed", they will also differ in some other ways).

Examples

A few languages distinguish three different postalveolar sibilant tongue shapes () such as the Sino-Tibetan Northern Qiang and Southern Qiang, which make such a distinction among affricates (but only a two-way distinction among fricatives) and the Northwest Caucasian languages Ubykh (now extinct) and Abkhaz. More common are languages such as Mandarin Chinese and Polish, which distinguish two postalveolar sibilants, typically since they are maximally distinct.

The attested possibilities, with exemplar languages, are as follows. IPA diacritics are simplified, and some articulations would require two diacritics to be fully specified, but only one is used to keep the results legible without the need for OpenType IPA fonts. Peter Ladefoged had resurrected an obsolete IPA symbol, the under dot, placed under the alveolars ⟨⟩ to indicate apical postalveolar, which is normally included in the category of retroflex consonants. The notation ⟨⟩ is sometimes reversed, and either may also be called 'retroflex' and written ⟨⟩. The more typical IPA transcriptions would be ⟨⟩ for laminal retroflex and ⟨⟩ or ⟨⟩ for apical postalveolar (⟨⟩ without diacritics for subapical retroflex). Laminal closed postalveolar would approximately be ⟨⟩, with the bridge above diacritic used for dentolabials, as the tongue touches the lower teeth.