The voiceless alveolar bilabially trilled affricate, [t̪͡ʙ̥] (occasionally written "t^p"), is one of the world's rarest sounds. It is reported from a few words in the Chapacuran languages, Wari’ and Oro Win, and recently also from the neighboring Muran language Pirahã. The Chapacura-Wanham languages are a nearly extinct Native American language family of South America. ... The Muran language family is a language family of Brazil. ... The Pirahã language is a language spoken by Pirahã people of Brazil. ...

[tʙ̥] is considered to be a single consonant in these languages because they do not otherwise have bilabial trills or consonant clusters. This is a stronger version of the argument made for [dʒ] being a single sound in English.

[tʙ̥] will regularly be trilled with three contact oscillations, as is normal for alveolar trills. However, trills are occasionally pronounced as fricatives in many languages, especially in slurred speech. When this happens to [tʙ̥], it is pronounced [tpɸ]. The alveolar trill is a type of consonantal sound, used in some spoken languages (such as Spanish, Armenian, and Polish). ... In phonetics, a trill is a consonantal sound produced by vibrations between the articulator and the place of articulation. ...

In the Chapacuran languages at least, [tʙ̥] is reported almost exclusively before rounded vowels. This probably has something to say about the development of this sound.

In Wari’ the sound is only known from two dozen words. A few of these are: