b (Pinyin) p (IPA)

Voiceless bilabial stop
The voiceless bilabial stop is a type of consonantal sound used in many spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨p⟩, and the equivalent X-SAMPA symbol is p. The voiceless bilabial stop in English is spelled with 'p', as in speed.

Features of the voiceless bilabial stop:

• Its manner of articulation is occlusive, which means it is produced by obstructing airflow in the vocal tract. Since the consonant is also oral, with no nasal outlet, the airflow is blocked entirely, and the consonant is a stop.
• Its place of articulation is bilabial, which means it is articulated with both lips.
• Its phonation is voiceless, which means it is produced without vibrations of the vocal cords. In some languages the vocal cords are actively separated, so it is always voiceless; in others the cords are lax, so that it may take on the voicing of adjacent sounds.
• 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.
• The airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the lungs and diaphragm, as in most sounds.