In addition, sibilants are absent from most Australian Aboriginal languages, in which fricatives are rare; however, [s] does occur in Kalaw Lagaw Ya.
It is a sibilant sound and is found most notably in a number of languages in a linguistic area covering northern and central Iberia.
In Romance languages, it occurs as the normal voiceless alveolar sibilant in Astur-Leonese, Castilian Spanish, Catalan, Galician, northern European Portuguese, and some Occitan dialects.
Outside this area, it also occurs in a few dialects of Latin American Spanish (e.g. Antioqueño and Pastuso, in Colombia).
In medieval times, it occurred in a wider area, including the Romance languages spoken in most or all of France and Iberia (Old Spanish, Galician-Portuguese, Catalan, French, etc.
This occurred, for example, in English borrowings from Old French (e.g. push from pousser, cash from caisse); in Polish borrowings from medieval German (e.g. kosztować from kosten, żur from sūr (contemporary sauer)); and in representations of Mozarabic (an extinct medieval Romance language once spoken in southern Spain) in Arabic characters.
One of the clearest descriptions of this sound is from Obaid:[6] "There is a Castilian s, which is a voiceless, concave, apicoalveolar fricative: The tip of the tongue turned upward forms a narrow opening against the alveoli of the upper incisors.
In general, older European languages only had a single pronunciation of s. In Romance languages, [s] was reached from -ti-, -ci-, -ce- ([ti], [ki], [ke]) clusters that eventually became [ts], [tsi], [tse] and later [s], [si], [se] (as in Latin fortia "force", civitas "city", centum "hundred"), while [ʃ] was reached: In High German, [s] was reached through a [t] > [ts] > [s] process, as in German Wasser compared to English water.
In English, the same process of Romance [ts] > [s] occurred in Norman-imported words, accounting for modern homophones sell and cell.
The Germanic-speaking regions that did not have either phenomenon have normally preserved the apical [s̺], that is, Icelandic, Dutch and many Scandinavian lects.
It equally well could have been an areal feature inherited from the prehistoric languages of Western Europe, as evidenced by its occurrence in modern Basque.
For the same reasons, it can be speculated that retracted [s̺] was the pronunciation of Proto-Germanic s. Its presence in many branches of Indo-European and its presence particularly in the more conservative languages inside each branch (e.g. Icelandic, Spanish), as well as being found in disparate areas, such as the Baltic languages and Greece, suggests it could have ultimately been the main allophone of Proto-Indo-European s,[5] known for ranging from [s] to as far as [ɕ].
But Neapolitan has a medieval S becoming either [s] or [ʃ] depending on context, much as in European Portuguese, which could attest to the previous existence of [s̺] in the Italian Peninsula.
The term "voiceless alveolar sibilant" is potentially ambiguous in that it can refer to at least two different sounds.
Various languages of northern Iberia (e.g., Astur-Leonese, Catalan, Basque, Galician, Portuguese and Spanish) have a so-called "voiceless apico-alveolar sibilant" that lacks the strong hissing of the [s] described in this article but has a duller, more "grave" sound quality somewhat reminiscent of a voiceless retroflex sibilant.
As the International Phonetic Alphabet does not have separate symbols for the alveolar consonants (the same symbol is used for all coronal places of articulation that are not palatalized), this sound is usually transcribed ⟨θ̠⟩, occasionally ⟨θ͇⟩ (retracted or alveolarized [θ], respectively), ⟨ɹ̝̊⟩ (constricted voiceless [ɹ]), or ⟨t̞⟩ (lowered [t]).
[87] Tapped fricatives are occasionally reported in the literature, though these claims are not generally independently confirmed and so remain dubious.