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 B\_0

This sound is typologically extremely rare. It occurs in languages such as Pará Arára^[1] and Sercquiais.^{[citation needed]}

Only a few languages contrast voiced and voiceless bilabial trills phonemically – e.g. Mangbetu of Congo and Ninde of Vanuatu.^[2]^[3]

There is also a very rare voiceless alveolar bilabially trilled affricate, [t̪͡ʙ̥] (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 /tʷ/ of Abkhaz and Ubykh, but in those languages it is more often realised by a doubly articulated stop [t͡p]. In the Chapacuran languages, [tʙ̥] is reported almost exclusively before rounded vowels such as [o] and [y].

Additionally, Lese has another rare trilled affricate, a labial–velar trilled affricate [k͡pʙ̥], which occurs as an allophone of the voiceless labial–velar plosive [k͡p].^[4]

Features

Features of the bilabial trill:

Its manner of articulation is trill, which means it is produced by directing air over an articulator so that it vibrates.
Its place of articulation is bilabial, which means it is articulated with both lips.
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.
Because the sound is not produced with airflow over the tongue, the central–lateral dichotomy does not apply.
Its airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the intercostal muscles and abdominal muscles, as in most sounds.

Language	Word	IPA	Meaning	Notes
Ahamb^[5]	[ŋãˈʙ̥̍s]		'it foams'	Contrasts /ʙ̥, ᵐʙ, ⁿᵈr/.
Lese^[4]	[uk͡pʙ̥u]		'head'	Allophone of /k͡p/
Neverver^[6]	[naɣaᵐʙ̥]		'fire, firewood'
Pará Arára^[7]	[ʙ̥uta]		'to throw away'
Ubykh^[8]	тваҳəбза/tuaqhəbza	[t͡ʙ̥aχəbza]	'Ubykh language'	Allophone of /tʷ/. See Ubykh phonology

^ de Souza, Isaac Costa (2010). "3". A Phonological Description of "Pet Talk" in Arara (MA). University of North Dakota. S2CID 61247622.
^ Linguist Wins Symbolic Victory for 'Labiodental Flap'. NPR (2005-12-17). Retrieved on 2010-12-08.
^ LINGUIST List 8.45: Bilabial trill. Linguistlist.org. Retrieved on 2010-12-08.
^ ^a ^b Didier Demolin, Bernard Teston (September 1997). "Phonetic characteristics of double articulations in some Mangbutu-Efe languages" (PDF). International Speech Communication Association: 803–806.
^ Rangelov, Tihomir. 2019. The bilabial trills of Ahamb (Vanuatu): Acoustic and articulatory properties. In S. Calhoun, P. Escudero, M. Tabain and P. Warren (eds),Proceedings of the 19th International Congress of Phonetic Sciences, Melbourne, Australia 2019. Canberra, Australasian Speech Science and Technology Association Inc.: 1292-1296.
^ See pp.33-34 of: Barbour, Julie (2012). A Grammar of Neverver. Germany: Mouton de Gruyter. ISBN 9783110289619.
^ de Souza, Isaac Costa (2010). "3" (PDF). A Phonological Description of "Pet Talk" in Arara (MA). SIL Brazil. Archived from the original (PDF) on 2013-10-12. Retrieved 2014-01-09.
^ Ladefoged (2005:165)