Voiced bilabial fricative | |||
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β | |||
IPA Number | 127 | ||
Audio sample | |||
Encoding | |||
Entity (decimal) | β | ||
Unicode (hex) | U+03B2 | ||
X-SAMPA | B | ||
Braille | |||
|
Voiced bilabial approximant | |
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β̞ | |
ʋ̟ | |
Audio sample | |
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 official symbol ⟨β⟩ is the Greek letter beta.
This letter is also often used to represent the bilabial approximant, though that is more precisely written with a lowering diacritic, that is ⟨β̞⟩ and/or ⟨ʋʼ⟩ That sound may also be transcribed as an advanced labiodental approximant ⟨ʋ̟⟩, in which case the diacritic is again frequently omitted, since no contrast is likely.[1][2] It has been proposed that either a turned ⟨β⟩ (approximately 𐅸),reversed ⟨β⟩ or a affricate ⟨βθ⟩ can be used as a dedicated symbol for the bilabial approximant, but despite occasional usage this has not gained general acceptance.[3]
It is extremely rare for a language to make a phonemic contrast between the voiced bilabial fricative and the bilabial approximant. The Mapos Buang language of New Guinea contains this contrast. Its bilabial approximant is analyzed as filling a phonological gap in the labiovelar series of the consonant system rather than the bilabial series.[4] Proto-Germanic[5] and Proto-Italic[6] are also reconstructed as having had this contrast, albeit with [β] being an allophone for another consonant in both cases. In Bashkir language, it is an intervocal allophone of /b/, and it is contrastive with /w/: балабыҙ [bɑɫɑˈβɯð] 'our child', балауыҙ [bɑɫɑˈwɯð] 'wax'.
The bilabial fricative is diachronically unstable (likely to be considerably varied between dialects of a language that makes use of it) and is likely to shift to [v].[7]
The sound is not the primary realization of any sound in English dialects except for Chicano English, but it can be produced by approximating the normal English [v] between the lips; it can also sometimes occur as an allophone of /v/ after bilabial consonants.