The Voiceless bilabial plosive reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Voiceless bilabial plosive

The voiceless 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 p, and the equivalent X-SAMPA symbol is p. The voiceless bilabial plosive in English is spelled with 'p', as in pit or speed.

IPA - Unicode	p
IPA - image
X-SAMPA	p

Features of this consonant:

• Its manner of articulation is plosive or stop, which means it is produced by obstructing airflow in the vocal tract.
• Its place of articulation is bilabial which means it is articulated with both lips,
• Its phonation type is voiceless, which means it is produced without vibrations of the vocal cords.
• It is an oral consonant, which means air is allowed to escape through the mouth.
• It is a central consonant, which means it is produced by allowing the airstream to flow over the center of the tongue, rather than the sides.
• The airstream mechanism is pulmonic egressive, which means it is articulated by pushing air out of the lungs and through the vocal tract, rather than from the glottis or the mouth.

The [p] sound is a very common sound cross-linguistically. Most languages have at least a plain [p], and some distinguish more than one variety. Many Indian languages, such as Hindi, have a two-way contrast between aspirated and plain [p]. English has both aspirated and plain [p], but they are allophones.

Varieties of the voiceless bilabial plosive

IPA	Description
p	plain p
pʰ	aspirated p
pʲ	palatalized p
pʷ	labialized p
p˺	unreleased p
p̬	voiced p
pʼ	ejective p