In many of the languages that contains bilabial trill, it only occurs as part of a prenasalised bilabial stop with trilled release, [mbʙ]. This developed historically from a prenasalized stop before a relatively high back vowel, such as [mbu]. In such instances, these sounds are usually still limited to the environment of a following [u].
There is also voiceless alveolar bilabially trilled affricate ([t̪͡ʙ̥], sometimes "tᵖ"), which is not often used. It is found in Pirahã and from a few words in the Chapacuran languages Wari’ and Oro Win. The sound also appears as an allophone of the labialized voiceless alveolar plosive/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].