This article is about the consonantal sound. For the Greek letter, see Phi (letter)
. For the Cyrillic letter, see Ef (Cyrillic)
The voiceless 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 ⟨ɸ⟩. For English-speakers, it is easiest to think of the sound as an f-sound made only with the lips, instead of the upper teeth and lower lip.
Features of the voiceless bilabial fricative:
- Its manner of articulation is fricative, which means it is produced by constricting air flow through a narrow channel at the place of articulation, causing turbulence.
- 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.
See also 
- Ladefoged, Peter (2005), Vowels and Consonants (Second ed.), Blackwell
- Okada, Hideo (1991), "Japanese", Journal of the International Phonetic Association 21 (2): 94–97, doi:10.1017/S002510030000445X
- Pérez, Ramón Morillo-Velarde; Aguilar, Rafael Cano; Jiménez, Antonio Narbona (1998), El Español hablado en Andalucía, ISBN 84-344-8225-8