Place of articulation



In articulatory phonetics, the place of articulation (also point of articulation) of a consonant is the point of contact where an obstruction occurs in the vocal tract between an articulatory gesture, an active articulator (typically some part of the tongue), and a passive location (typically some part of the roof of the mouth). Along with the manner of articulation and the phonation, this gives the consonant its distinctive sound.

The terminology in this article has been developed to precisely describe all the consonants in all the world's spoken languages. No known language distinguishes all of the places described here, so less precision is needed to distinguish the sounds of a particular language.

Overview
The human voice produces sounds in the following manner:


 * 1) Air pressure from the lungs creates a steady flow of air through the trachea (windpipe), larynx (voice box) and pharynx (back of the throat).
 * 2) The vocal folds in the larynx vibrate, creating fluctuations in air pressure that are known as sound waves.
 * 3) Resonances in the vocal tract modify these waves according to the position and shape of the lips, jaw, tongue, soft palate, and other speech organs, creating formant regions and thus different qualities of sonorant (voiced) sound.
 * 4) Mouth and nose openings radiate the sound waves into the environment.

The larynx
The larynx or voice box is a cylindrical framework of cartilage that serves to anchor the vocal folds. When the muscles of the vocal folds contract, the airflow from the lungs is impeded until the vocal folds are forced apart again by the increasing air pressure from the lungs. This process continues in a periodic cycle that is felt as a vibration (buzzing). In singing, the vibration frequency of the vocal folds determines the pitch of the sound produced. Voiced phonemes such as the pure vowels are, by definition, distinguished by the buzzing sound of this periodic oscillation of the vocal cords.

The lips of the mouth can be used in a similar way to create a similar sound, as any toddler or trumpeter can demonstrate. A rubber balloon, inflated but not tied off and stretched tightly across the neck produces a squeak or buzz, depending on the tension across the neck and the level of pressure inside the balloon. Similar actions, with similar results, occur when the vocal cords are contracted or relaxed across the larynx.

Place of articulation (passive)
The passive place of articulation is the place on the more stationary part of the vocal tract where the articulation occurs. It can be anywhere from the lips, upper teeth, gums, or roof of the mouth to the back of the throat. Although it is a continuum, there are several contrastive areas such that languages may distinguish consonants by articulating them in different areas, but few languages will contrast two sounds within the same area unless there is some other feature which contrasts as well. The following areas are contrastive:
 * The upper lip ()
 * The upper teeth, either on the edge of the teeth or inner surface ()
 * The alveolar ridge, the gum line just behind the teeth ()
 * The back of the alveolar ridge ()
 * The hard palate on the roof of the mouth ()
 * The soft palate further back on the roof of the mouth ()
 * The uvula hanging down at the entrance to the throat ()
 * The throat itself, the pharynx ()
 * The epiglottis at the entrance to the windpipe, above the voice box ()

These regions are not strictly separated. For instance, in many languages the surface of the tongue contacts a relatively large area from the back of the upper teeth to the alveolar ridge; this is common enough to have received its own name, . Likewise, the alveolar and post-alveolar regions merge into each other, as do the hard and soft palate, the soft palate and the uvula, and indeed all adjacent regions. Terms like pre-velar (intermediate between palatal and velar), post-velar (between velar and uvular), and upper vs lower pharyngeal may be used to specify more precisely where an articulation takes place. However, although a language may contrast pre-velar and post-velar sounds, it will not also contrast them with palatal and uvular sounds (of the same type of consonant), so that contrasts are limited to the number above if not always their exact location.

Place of articulation (active)
The articulatory gesture of the active place of articulation involves the more mobile part of the vocal tract. This is typically some part of the tongue or lips. The following areas are known to be contrastive:
 * The lower lip ()
 * Various parts of the front of the tongue ():
 * The tip of the tongue ()
 * The upper front surface of the tongue just behind the tip, called the blade of the tongue ()
 * The surface of the tongue under the tip ()
 * The body of the tongue ()
 * The base root of the tongue in the throat ()
 * The epiglottis, the flap at the base of the tongue ()
 * The aryepiglottic folds at the entrance to the larynx (also )
 * The glottis ()

In bilabial consonants both lips move, so the articulatory gesture is bringing together the lips, but by convention the lower lip is said to be active and the upper lip passive. Similarly, in linguolabial consonants the tongue contacts the upper lip with the upper lip actively moving down to meet the tongue; nonetheless, in this gesture the tongue is conventionally said to be active and the lip passive, if for no other reason than the fact that the parts of the mouth below the vocal tract are typically active, and those above the vocal tract typically passive.

In dorsal gestures different parts of the body of the tongue contact different parts of the roof of the mouth, but this cannot be independently controlled, so they are all subsumed under the term dorsal. This is unlike coronal gestures involving the front of the tongue, which is more flexible.

The epiglottis may be active, contacting the pharynx, or passive, being contacted by the aryepiglottal folds. Distinctions made in these laryngeal areas are very difficult to observe and are the subject of ongoing investigation, with several as-yet unidentified combinations thought possible.

The glottis acts upon itself. There is a sometimes fuzzy line between glottal, aryepiglottal, and epiglottal consonants and phonation, which uses these same areas.

Unlike the passive articulation, which is a continuum, there are five discrete active articulators: the lip (labial consonants), the flexible front of the tongue (coronal consonants: laminal, apical, and subapical), the middle–back of the tongue (dorsal consonants), the root of the tongue together with the epiglottis (radical consonants), and the larynx (laryngeal consonants). These articulators are discrete in that they can act independently of each other, and two or more may work together in what is called coarticulation (see below). The distinction between the various coronal articulations, laminal, apical, and subapical, are however a continuum without clear boundaries.

Table of gestures and passive articulators and resulting places of articulation
The following table shows the possible combinations of active and passive articulators.

The possible locations where sibilants as well as non-sibilants can occur are indicated in dashed red. For sibilants, there are additional complications involving tongue shape; see the article on sibilants for a chart of possible articulations.

A precise vocabulary of compounding the two places of articulation is sometimes seen. However, this is usually reduced to the passive articulation, which is generally sufficient. Thus dorsal–palatal, dorsal–velar, and dorsal–uvular are usually just called "palatal", "velar", and "uvular". Where there is ambiguity, additional terms have been invented, so subapical–palatal is more commonly called "retroflex".

NOTE: Additional shades of passive articulation are sometimes specified using pre- or post-, for example prepalatal (near the border between the postalveolar region and the hard palate; prevelar (at the back of the hard palate, also post-palatal or even medio-palatal for the middle of the hard palate); or postvelar (near the border of the soft palate and the uvula). These can be useful in the precise description of sounds that are articulated somewhat farther forward or back than a prototypical consonant; for this purpose, the "fronted" and "retracted" IPA diacritics can be used. However, none of these additional shades are needed to phonemically distinguish two consonants in a single language.

Homorganic consonants
Consonants that have the same place of articulation, such as the alveolar sounds in English, are said to be homorganic. Similarly, labial and velar  are homorganic. A homorganic nasal rule, an instance of assimilation, operates in many languages, where a nasal consonant must be homorganic with a following stop. We see this with English intolerable but implausible; another example is found in Yoruba, where the present tense of ba "hide" is mba "is hiding", while the present of sun "sleep" is nsun "is sleeping".

Central and lateral articulation
The tongue contacts the mouth with a surface, which has two dimensions: length and width. So far only points of articulation along its length have been considered. However, articulation varies along its width as well. When the airstream is directed down the center of the tongue, the consonant is said to be central. If, however, it is deflected off to one side, escaping between the side of the tongue and the side teeth, it is said to be lateral. Nonetheless, for simplicity's sake the place of articulation is assumed to be the point along the length of the tongue, and the consonant may in addition be said to be central or lateral. That is, a consonant may be lateral alveolar, like English (the tongue contacts the alveolar ridge, but allows air to flow off to the side), or lateral palatal, like Castilian Spanish ll. Some Indigenous Australian languages contrast dental, alveolar, retroflex, and palatal laterals, and many Native American languages have lateral fricatives and affricates as well.

Coarticulation
Some languages have consonants with two simultaneous places of articulation, called coarticulation. When these are doubly articulated, the articulators must be independently movable, and therefore there may only be one each from the major categories labial, coronal, dorsal, radical, and laryngeal.

The only common doubly articulated consonants are labial–velar stops like, , and less commonly , which are found throughout West and Central Africa. Other combinations are rare. They include labial–(post)alveolar stops, found as distinct consonants only in a single language in New Guinea, and a uvular–epiglottal stop, , found in Somali.

More commonly, coarticulation involves secondary articulation of an approximantic nature, in which case both articulations can be similar, such as labialized labial or palatalized velar. This is the case of English, which is a velar consonant with secondary labial articulation.

Common coarticulations include:


 * Labialization, rounding the lips while producing the obstruction, as in and English.
 * Palatalization, raising the body of the tongue toward the hard palate while producing the obstruction, as in Russian and.
 * Velarization, raising the back of the tongue toward the soft palate (velum), as in the English dark el, (also transcribed ).
 * Pharyngealization, constriction of the throat (pharynx), such as Arabic "emphatic".

Production of vowels
A vowel is any phoneme in which airflow is impeded only or mostly by the voicing action of the vocal cords.

The well-defined fundamental frequency provided by the vocal cords in voiced phonemes is only a convenience, however, not a necessity, since a strictly unvoiced whisper is still quite intelligible. Our interest is therefore most focused on further modulations of and additions to the fundamental tone by other parts of the vocal apparatus, determined by the variable dimensions of oral, pharyngeal, and even nasal cavities.

Formants
Formants are the resonant frequencies of the vocal tract that emphasize particular voice harmonics near in frequency to the resonance, or turbulent non-periodic energy (i.e. noise) near the formant frequency in the case of whispered speech. The formants tell a listener what vowel is being spoken.