Strident vowels are fairly common in Khoisan languages, which contrasts them with simple pharyngealized vowels. Stridency is used in onomatopoeia in Zulu and Lamba.[3][page needed] Stridency may be a type of phonation called harsh voice. A similar phonation, without the trill, is called ventricular voice; both have been called pressed voice.[citation needed]Bai, of southern China, has a register system that has allophonic strident and pressed vowels.
There is no official symbol for stridency in the IPA, but a superscript ⟨ʢ⟩ (for a voiced epiglottal trill) is often used.[citation needed] In some literature, a subscript double tilde (≈) is sometimes used.[1]
It has been accepted into Unicode, at code points U+1DFD and U+107B4.
^Miller-Ockhuizen, Amanda (2003). The phonetics and phonology of gutturals: case study from Juǀʼhoansi. Outstanding dissertations in Linguistics. New York City, NY: Routledge. p. 99. doi:10.4324/9780203506400. ISBN978-0-415-86141-0. LCCN2003046887.
Moisik, Scott; Czaykowska-Higgins, Ewa; Esling, John H. (Winter 2012). Loughran, Jenny; McKillen, Alanah (eds.). "The Epilaryngeal Articulator: A New Conceptual Tool for Understanding Lingual-Laryngeal Contrasts". McGill Working Papers in Linguistics. 22 (1). McGill University.