High Quality Content by WIKIPEDIA articles! The voiceless palato-alveolar fricative or domed postalveolar fricative (IPA [?]) is a type of consonantal sound, used in some spoken languages. The sound occurs in many languages and, as in English, French and Italian, where it may have simultaneous lip rounding ([??]), although this is rarely indicated. The symbol in the International Phonetic Alphabet that represents this sound is , the letter esh introduced by Isaac Pitman (not to be confused with the integral sign ?), and the equivalent X-SAMPA symbol is S. An alternative symbol used in some older and American linguistic literature is ?, an s with há?ek, originating with the Czech alphabet of Jan Hus (also used in Gaj's Latin alphabet as well as scientific and ISO 9 transliterations of Cyrillic).