Articulatory phonetics
The field of articulatory phonetics is a subfield of phonetics that studies articulation and ways that humans produce speech. Articulatory phoneticians explain how humans produce speech sounds via the interaction of different physiological structures. Generally, articulatory phonetics is concerned with the transformation of aerodynamic energy into acoustic energy. Aerodynamic energy refers to the airflow through the vocal tract. Its potential form is air pressure; its kinetic form is the actual dynamic airflow. Acoustic energy is variation in the air pressure that can be represented as sound waves, which are then perceived by the human auditory system as sound.
Respiratory sounds can be produced by expelling air from the lungs. However, to vary the sound quality in a way useful for speaking, two speech organs normally move towards each other to contact each other to create an obstruction that shapes the air in a particular fashion. The point of maximum obstruction is called the place of articulation, and the way the obstruction forms and releases is the manner of articulation. For example, when making a p sound, the lips come together tightly, blocking the air momentarily and causing a buildup of air pressure. The lips then release suddenly, causing a burst of sound. The place of articulation of this sound is therefore called ', and the manner is called '.
Components
The vocal tract can be viewed through an aerodynamic-biomechanic model that includes three main components:- air cavities
- pistons
- air valves
Pistons are initiators. The term initiator refers to the fact that they are used to initiate a change in the volumes of air cavities, and, by Boyle's law, the corresponding air pressure of the cavity. The term initiation refers to the change. Since changes in air pressures between connected cavities lead to airflow between the cavities, initiation is also referred to as an airstream mechanism. The three pistons present in the articulatory system are the larynx, the tongue body, and the physiological structures used to manipulate lung volume. The lung pistons are used to initiate a pulmonic airstream. The larynx is used to initiate the glottalic airstream mechanism by changing the volume of the supraglottal and subglottal cavities via vertical movement of the larynx. Ejectives and implosives are made with this airstream mechanism. The tongue body creates a velaric airstream by changing the pressure within the oral cavity: the tongue body changes the mouth subcavity. Click consonants use the velaric airstream mechanism. Pistons are controlled by various muscles.
Valves regulate airflow between cavities. Airflow occurs when an air valve is open and there is a pressure difference between the connecting cavities. When an air valve is closed, there is no airflow. The air valves are the vocal folds, which regulate between the supraglottal and subglottal cavities, the velopharyngeal port, which regulates between the oral and nasal cavities, the tongue, which regulates between the oral cavity and the atmosphere, and the lips, which also regulate between the oral cavity and the atmosphere. Like the pistons, the air valves are also controlled by various muscles.
Initiation
To produce any kind of sound, there must be movement of air. To produce sounds that people can interpret as spoken words, the movement of air must pass through the vocal folds, up through the throat and, into the mouth or nose to then leave the body. Different sounds are formed by different positions of the mouth—or, as linguists call it, "the oral cavity".Consonants
Consonants are speech sounds that are articulated with a complete or partial closure of the vocal tract. They are generally produced by the modification of an airstream exhaled from the lungs. The respiratory organs used to create and modify airflow are divided into three regions: the vocal tract, the larynx, and the subglottal system. The airstream can be either egressive or ingressive. In pulmonic sounds, the airstream is produced by the lungs in the subglottal system and passes through the larynx and vocal tract. Glottalic sounds use an airstream created by movements of the larynx without airflow from the lungs. Click consonants are articulated through the rarefaction of air using the tongue, followed by releasing the forward closure of the tongue.Place of articulation
Consonants are pronounced in the vocal tract, usually in the mouth. In order to describe the place of articulation, the active and passive articulator need to be known. In most cases, the active articulators are the lips and tongue. The passive articulator is the surface on which the constriction is created. Constrictions made by the lips are called labials. Constrictions can be made in several parts of the vocal tract, broadly classified into coronal, dorsal and radical places of articulation. Coronal articulations are made with the front of the tongue, dorsal articulations are made with the back of the tongue, and radical articulations are made in the pharynx. These divisions are not sufficient for distinguishing and describing all speech sounds. For example, in English the sounds and are both coronal, but they are produced in different places of the mouth. To account for this, more detailed places of articulation are needed based upon the area of the mouth in which the constriction occurs.Labial consonants
Articulations involving the lips can be made in three different ways: with both lips, with one lip and the teeth, and with the tongue and the upper lip. Depending on the definition used, some or all of these kinds of articulations may be categorized into the class of labial articulations. Ladefoged and Maddieson propose that linguolabial articulations be considered coronals rather than labials, but make clear this grouping, like all groupings of articulations, is equivocal and not cleanly divided. Linguolabials are included in this section as labials given their use of the lips as a place of articulation.Bilabial consonants are made with both lips. In producing these sounds the lower lip moves farthest to meet the upper lip, which also moves down slightly, though in some cases the force from air moving through the aperture may cause the lips to separate faster than they can come together. Unlike most other articulations, both articulators are made from soft tissue, and so bilabial stops are more likely to be produced with incomplete closures than articulations involving hard surfaces like the teeth or palate. Bilabial stops are also unusual in that an articulator in the upper section of the vocal tract actively moves downwards, as the upper lip shows some active downward movement.
Labiodental consonants are made by the lower lip rising to the upper teeth. Labiodental consonants are most often fricatives while labiodental nasals are also typologically common. There is debate as to whether true labiodental plosives occur in any natural language, though a number of languages are reported to have labiodental plosives including Zulu, Tonga, and Shubi. Labiodental affricates are reported in Tsonga which would require the stop portion of the affricate to be a labiodental stop, though Ladefoged and Maddieson raise the possibility that labiodental affricates involve a bilabial closure like "pf" in German. Unlike plosives and affricates, labiodental nasals are common across languages.
Linguolabial consonants are made with the blade of the tongue approaching or contacting the upper lip. Like in bilabial articulations, the upper lip moves slightly towards the more active articulator. Articulations in this group do not have their own symbols in the International Phonetic Alphabet, rather, they are formed by combining an apical symbol with a diacritic implicitly placing them in the coronal category. They exist in a number of languages indigenous to Vanuatu such as Tangoa, though early descriptions referred to them as apical-labial consonants. The name "linguolabial" was suggested by Floyd Lounsbury given that they are produced with the blade rather than the tip of the tongue.
Coronal consonants
Coronal consonants are made with the tip or blade of the tongue and, because of the agility of the front of the tongue, represent a variety not only in place but in the posture of the tongue. The coronal places of articulation represent the areas of the mouth where the tongue contacts or makes a constriction, and include dental, alveolar, and post-alveolar locations. Tongue postures using the tip of the tongue can be apical if using the top of the tongue tip, laminal if made with the blade of the tongue, or sub-apical if the tongue tip is curled back and the bottom of the tongue is used. Coronals are unique as a group in that every manner of articulation is attested. Australian languages are well known for the large number of coronal contrasts exhibited within and across languages in the region.Dental consonants are made with the tip or blade of the tongue and the upper teeth. They are divided into two groups based upon the part of the tongue used to produce them: apical dental consonants are produced with the tongue tip touching the teeth; interdental consonants are produced with the blade of the tongue as the tip of the tongue sticks out in front of the teeth. No language is known to use both contrastively though they may exist allophonically.
Alveolar consonants are made with the tip or blade of the tongue at the alveolar ridge just behind the teeth and can similarly be apical or laminal.
Crosslinguistically, dental consonants and alveolar consonants are frequently contrasted leading to a number of generalizations of crosslinguistic patterns. The different places of articulation tend to also be contrasted in the part of the tongue used to produce them: most languages with dental stops have laminal dentals, while languages with alveolar stops usually have apical stops. Languages rarely have two consonants in the same place with a contrast in laminality, though Taa is a counterexample to this pattern. If a language has only one of a dental stop or an alveolar stop, it will usually be laminal if it is a dental stop, and the stop will usually be apical if it is an alveolar stop, though for example Temne and Bulgarian do not follow this pattern. If a language has both an apical and laminal stop, then the laminal stop is more likely to be affricated like in Isoko, though Dahalo show the opposite pattern with alveolar stops being more affricated.
Retroflex consonants have several different definitions depending on whether the position of the tongue or the position on the roof of the mouth is given prominence. In general, they represent a group of articulations in which the tip of the tongue is curled upwards to some degree. In this way, retroflex articulations can occur in several different locations on the roof of the mouth including alveolar, post-alveolar, and palatal regions. If the underside of the tongue tip makes contact with the roof of the mouth, it is sub-apical though apical post-alveolar sounds are also described as retroflex. Typical examples of sub-apical retroflex stops are commonly found in Dravidian languages, and in some languages indigenous to the southwest United States the contrastive difference between dental and alveolar stops is a slight retroflexion of the alveolar stop. Acoustically, retroflexion tends to affect the higher formants.
Articulations taking place just behind the alveolar ridge, known as post-alveolar consonants, have been referred to using a number of different terms. Apical post-alveolar consonants are often called retroflex, while laminal articulations are sometimes called palato-alveolar; in the Australianist literature, these laminal stops are often described as 'palatal' though they are produced further forward than the palate region typically described as palatal. Because of individual anatomical variation, the precise articulation of palato-alveolar stops can vary widely within a speech community.