The Voiced postalveolar fricative reference article from the English Wikipedia on 24-Apr-2004
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Voiced postalveolar fricative

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The voiced postalveolar fricative is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ʒ, and the equivalent X-SAMPA symbol is Z. The voiced postalveolar fricative occurs in English, although in only a handful of words, and it is the sound denoted by the letter "s" in treasure and the final sound of the word rouge.

IPA - Unicode ʒ
IPA - image Image:Xsampa-Z2.png
X-SAMPA Z
Sound sample

Features of this consonant: