The voiceless retroflex sibilant is a type of consonantal sound, used in some spokenlanguages. The symbol in the International Phonetic Alphabet that represents this sound is 〈ʂ〉. Like all the retroflex consonants, the IPA letter is formed by adding a rightward-pointing hook to the bottom of the ess (the letter used for the corresponding alveolar consonant). A distinction can be made between laminal, apical, and sub-apical articulations. Only one language, Toda, appears to have more than one voiceless retroflex sibilant, and it distinguishes subapical palatal from apical postalveolar retroflex sibilants; that is, both the tongue articulation and the place of contact on the roof of the mouth are different.
Its manner of articulation is sibilantfricative, which means it is generally produced by channeling air flow along a groove in the back of the tongue up to the place of articulation, at which point it is focused against the sharp edge of the nearly clenched teeth, causing high-frequency turbulence.
Its phonation is voiceless, which means it is produced without vibrations of the vocal cords. In some languages the vocal cords are actively separated, so it is always voiceless; in others the cords are lax, so that it may take on the voicing of adjacent sounds.
It is an oral consonant, which means air is allowed to escape through the mouth only.
It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides.