Editing Postalveolar consonant (section)

===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 language|Ubykh]] have the tongue tip resting directly against the lower teeth rather than in the hollowed area. Ladefoged and Maddieson<ref>{{SOWL}}</ref> 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 {{angbr IPA|ŝ, ẑ}} (that is not IPA notation; the [[obsolete IPA]] letters {{angbr IPA|ʆ, ʓ}} have occasionally been resurrected for these sounds).

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).