In articulatory phonetics, the place of articulation (also point of articulation) of a consonant is an approximate location along the vocal tract where its production occurs. It is a point where a constriction is made between an active and a passive articulator. Active articulators are organs capable of voluntary movement which create the constriction, while passive articulators are so called because they are normally fixed and are the parts with which an active articulator makes contact. Along with the manner of articulation and phonation, the place of articulation gives the consonant its distinctive sound. Since vowels are produced with an open vocal tract, the point where their production occurs cannot be easily determined. Therefore, they are not described in terms of a place of articulation but by the relative positions in vowel space. This is mostly dependent on their formant frequencies and less on the specific tongue position and lip rounding. The terminology used in describing places of articulation has been developed to allow specifying of all theoretically possible contrasts. No known language distinguishes all of the places described in the literature, so less precision is needed to distinguish the sounds of a particular language.
Overview The human voice produces sounds in the following manner:
Air pressure from the lungs creates a steady flow of air through the trachea (windpipe), larynx (voice box) and pharynx (back of the throat). Therefore, the air moves out of the lungs through a coordinated action of the diaphragm, abdominal muscles, chest muscles and rib cage. The vocal folds in the larynx vibrate, creating fluctuations in air pressure, known as sound waves. 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 so different qualities of sonorant (voiced) sound. Mouth radiates the sound waves into the environment. Nasal cavity adds resonance to some sounds such as [m] and [n] to give nasal quality of the so-called nasal consonants.
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. The 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.
Active articulators The active articulators are movable parts of the vocal apparatus that impede or direct the airstream, typically some part of the tongue or lips. There are five major parts of the vocal tract that move: the lips, the flexible front of the tongue, the body of the tongue, the root of the tongue together with the epiglottis, and the glottis. They are discrete in that they can act independently of each other, and two or more may work together in what is called coarticulation. The five main active parts can be further divided, as many languages contrast sounds produced within the same major part of the vocal apparatus. The following 9 degrees of active articulatory areas are known to be contrastive (sorted such that the top-most is in the front-most area of the mouth and the bottom-most is in the rear-most area of the mouth):
The lower lip (labial) Various parts of the front of the tongue (coronal): The tip of the tongue (apical) The upper front surface of the tongue just behind the tip, called the blade of the tongue (laminal) The surface of the tongue under the tip (subapical) The body of the tongue (dorsal) which is sometimes further divided into front and back The base a.k.a. root of the tongue and the throat (pharyngeal) The aryepiglottic fold inside the throat (aryepiglottal) The glottis at the very back of the windpipe (glottal) In bilabial consonants, both lips move so the articulatory gesture brings the lips together, 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, the tongue is conventionally said to be active and the lip passive if for no other reason than that the parts of the mouth below the vocal tract are typically active, and those above the vocal tract are typically passive. In dorsal gestures, different parts of the body of the tongue contact different parts of the roof of the mouth, but it cannot be independently controlled so they are all subsumed under the term dorsal. That 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, and several still-unidentified combinations are 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.
… excerpt ends here. Continue reading the full article.
