Voiceless postalveolar fricative

A voiceless postalveolar fricative is a type of consonantal sound used in some spoken languages. The International Phonetic Association uses the term voiceless postalveolar fricative only for the sound, but it also describes the voiceless postalveolar non-sibilant fricative , for which there are significant perceptual differences.

Voiceless palato-alveolar fricative
A voiceless palato-alveolar fricative or voiceless domed postalveolar fricative is a type of consonantal sound used in many languages, including English. In English, it is usually spelled $⟨sh⟩$, as in ship. The symbol in the International Phonetic Alphabet that represents this sound is ⟨&thinsp;ʃ&thinsp;⟩, the letter esh introduced by Isaac Pitman (not to be confused with the integral symbol $⟨∫⟩$). The equivalent X-SAMPA symbol is.

An alternative symbol is $⟨š⟩$, an s with a caron or háček, which is used in the Americanist phonetic notation and the Uralic Phonetic Alphabet, as well as in the scientific and ISO 9 transliterations of Cyrillic. It originated with the Czech orthography of Jan Hus and was adopted in Gaj's Latin alphabet and other Latin alphabets of Slavic languages. It also features in the orthographies of many Baltic, Finno-Samic, North American and African languages.

Features
Features of the voiceless palato-alveolar fricative:

Occurrence
In various languages, including English and French, it may have simultaneous labialization, i.e., although this is usually not transcribed.

Classical Latin did not have, though it does occur in most Romance languages. For example, $⟨ch⟩$ in French chanteur "singer" is pronounced. Chanteur is descended from Latin cantare, where $⟨c⟩$ was pronounced. The $⟨sc⟩$ in Latin scientia "science" was pronounced, but has shifted to in Italian scienza.

Similarly, Proto-Germanic had neither nor, yet many of its descendants do. In most cases, this or  descends from a Proto-Germanic. For instance, Proto-Germanic *skipą ("hollow object, water-borne vessel larger than a boat") was pronounced. The English word "ship" has been pronounced without the  the longest, the word being descended from Old English "scip", which already also had the , though the Old English spelling etymologically indicated that the old  had once been present.

This change took longer to catch on in West Germanic languages other than Old English, though it eventually did. The second West Germanic language to undergo this sound shift was Old High German. In fact, it has been argued that Old High German's was actually already, because a single  had already shifted to. Furthermore, by Middle High German, that had shifted to. After High German, the shift most likely then occurred in Low Saxon. After Low Saxon, Middle Dutch began the shift, but it stopped shifting once it reached, and has kept that pronunciation since. Then, most likely through influence from German and Low Saxon, North Frisian experienced the shift.

Then, Swedish quite swiftly underwent the shift, which resulted in the very uncommon phoneme, which, aside from Swedish, is only used in Colognian, a variety of High German, though not as a replacement for the standard High German  but a coronalized. However, the exact realization of Swedish varies considerably among dialects; for instance, in Northern dialects it tends to be realized as. See sj-sound for more details. Finally, the last to undergo the shift was Norwegian, in which the result of the shift was.

The sound in Russian denoted by $⟨ш⟩$ is commonly transcribed as a palato-alveolar fricative but is actually an apical retroflex fricative.

Voiceless postalveolar non-sibilant fricative
The voiceless postalveolar non-sibilant fricative is a consonantal sound. As the International Phonetic Alphabet does not have separate symbols for the post-alveolar consonants (the same symbol is used for all coronal places of articulation that are not palatalized), this sound is usually transcribed ⟨ɹ̠̊˔⟩ (retracted constricted voiceless ). The equivalent X-SAMPA symbol is.

Some scholars also posit the voiceless postalveolar approximant distinct from the fricative. The approximant may be represented in the IPA as ⟨ɹ̠̊⟩.

Features
However, it does not have the grooved tongue and directed airflow, or the high frequencies, of a sibilant.
 * Its place of articulation is postalveolar, which means it is articulated with either the tip or the blade of the tongue behind the alveolar ridge.