The voiced bilabial fricative is a type of consonantal sound, used in some spokenlanguages. 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 letterbeta. 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 [v]. In the English language, this sound is not used, but can be made by approximating the normal "v" sound between the two lips.
Its phonation is voiced, which means the vocal cords vibrate during the articulation. However, in some languages, such as Swiss German, it can just mean that this consonant is pronounced shorter and weaker than its voiceless counterpart, while its voicedness or lack thereof is not relevant. In such cases it's more accurate to call such sounds lenis or lax.
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.
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