Voiceless bilabial trill

The voiceless bilabial trill is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ʙ̥⟩. The X-SAMPA symbol is

This sound is typologically extremely rare. It occurs in languages such as Pará Arára and Sercquiais.

Only a few languages contrast voiced and voiceless bilabial trills phonemically – e.g. Mangbetu of Congo and Ninde of Vanuatu.

There is also a very rare voiceless alveolar bilabially trilled affricate, (written ⟨tᵖ̃⟩ in Everett & Kern) reported from Pirahã and from a few words in the Chapacuran languages Wariʼ and Oro Win. The sound also appears as an allophone of the labialized voiceless alveolar stop of Abkhaz and Ubykh, but in those languages it is more often realised by a doubly articulated stop. In the Chapacuran languages, is reported almost exclusively before rounded vowels such as  and.

Additionally, Lese has another rare trilled affricate, a labial–velar trilled affricate, which occurs as an allophone of the voiceless labial–velar plosive.

Features
Features of the bilabial trill: