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:
Point of tongue contact (laminal, apical, subapical) 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. Also, 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.
Position of tongue tip (laminal "closed") 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 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. Ladefoged and Maddieson term it a "
closed laminal postalveolar" articulation, which gives the sounds a quality that
JC Catford describes as "hissing-hushing" sounds. Catford transcribes them as (that 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). A laminal "closed" articulation could also 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. Also,
Peter Ladefoged has resurrected an obsolete IPA symbol, the under dot, to indicate the 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. ==Postalveolar non-sibilants==