Voiceless bilabial trill

A 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. Some sources have used a para-IPA symbol to transcribe this sound.
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.

Features

Features of a bilabial trill:

Occurrence

Prestopped trills and stops with trill release

There is also a very rare voiceless bilabially post-trilled dental or alveolar stop, reported from a few words in the Chapacuran languages Wariʼ, Itene, and Oro Win, as well as Sangtam, a Naga language. 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.
In some languages, the trill may be voiced, particularly when syllabic; see.