The voiced bilabial fricative is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨β⟩, and the equivalent X-SAMPA symbol is ⟨B⟩. The symbol ⟨β⟩ is the Greek letter beta. This symbol is also sometimes used to represent the bilabial approximant, though that is more clearly written with the lowering diacritic, ⟨β̞⟩. The bilabial fricative is diachronically unstable and is likely to shift to . In the English language, this sound is not used, but can be made by approximating the normal "v" sound between the two lips.
Read more about Voiced Bilabial Fricative: Features, Occurrence