Spanish Letters b and v

The Spanish letters b and v are pronounced the same. They have two phonetic realizations: the voiced bilabial plosive and the voiced bilabial fricative. The fricative occurs intervocalically and after consonants that are not nasals. The plosive occurs syllable-initially. 

The Spanish words baca (roof rack) and vaca (cow) are pronounced identically. The phonetic transcription is [baka]. The phonetic symbol for the fricative is [β]. This is also the symbol for the Greek letter beta.

In phonology the bilabial plosive is the phoneme. It has wider distribution than the fricative, which only occurs intervocalically and after consonants that are [-nasal]. Here are ten Spanish words with the plosive and the fricative: 

alba [β] (dawn)

bolsa [b] (bag)

embudo [b] (funnel) 

invierno [b] (winter)

libertad [β] (freedom)

lobo [β] (wolf)

nueve [β] (nine)

posible [b] (possible)

vino [b] (wine)

vuelo [b} (flight)

Spanish has no distinction between the letters b and v. Unlike in English and many other languages, Spanish has no voiced labiodental fricative as in very. The letters are realized as a bilabial plosive or bilabial fricative.