High Quality Content by WIKIPEDIA articles! The voiced bilabial plosive is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is b, and the equivalent X-SAMPA symbol is b. The voiced bilabial plosive occurs in English, and it is the sound denoted by the letter "b" in boy. Many Indian languages, such as Hindi, have a two-way contrast between aspirated and plain.