Language And Linguistics In Articulatory Phonetics

Published Date: 02 Nov 2017

The field of articulatory phonetics is a subfield of phonetics. In studying articulation, 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.[1]

The vocal tract can viewed through an aerodynamic-biomechanic model which includes three main components:

air cavities

pistons

air valves

Air cavities are containers of air molecules of specific volumes and masses. The main air cavities present in the articulatory system are the supraglottal cavity and the subglottal cavity. They are so-named because the glottis, the openable space between the vocal folds internal to the larynx, separates the two cavities. The supraglottal cavity or the oronasal cavity is divided into an oral subcavity (the cavity from the glottis to the lips excluding the nasal cavity) and a nasal subcavity (the cavity from the velopharyngeal port which can be closed by raising the velum to the nostrils). The subglottal cavity consists of the trachea and the lungs. The atmosphere external to the articulatory stem may also be consisted an air cavity whose potential connecting points with respect to the body are the nostrils and the lips.

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 (particularly the floor and the walls of the chest). The lung pistons are used to initiate a pulmonic airstream (found in all human languages). 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 (with a closed glottis). Ejectives and implosives are made with this airstream mechanism. The tongue body creates a velaric airsteam by changing the pressure within in 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 in the connecting cavities. When an air valve is closed, there is no airflow. The air valves are the vocal folds (the glottis) 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.

Theoretically, any sound could be used as a speech sound provided the human vocal tract is capable of producing it and the human ear capable of hearing it.  Actually only a few hundred different sounds or types of sounds occur in languages known to exist today, considerably fewer than the vocal tract is capable of producing. 

      Thus, all speech sounds result from air being somehow obstructed or modified within the vocal tract. This involves 3 processes working together:

a) the airstream process--the source of air used in making the sound.

b) the phonation process--the behavior of the vocal cords in the glottis during the production of the sound.

c) the oro-nasal process--the modification of that flow of air in the vocal track (from the glottis to the lips and nose).

The airstream process

      The first major way to categorize sounds according to phonetic features is by the source of air.  Where does the air come from that is modified by the vocal organs? Languages can use any of three airstream mechanisms to produce sounds.  

      One airstream mechanism is by far the most important for producing sounds in the world's languages.  Most sounds in the world's languages are produced by manipulating air coming into the vocal tract as it is being exhaled by the lungs, a method referred to as the pulmonic egressive airstream mechanism.  Sounds made by manipulating air as it is exhaled from the lungs are called pulmonic egressive sounds.  Virtually all sounds in English and other European languages are produced by manipulating exhaled air.  And most sounds in other languages are also pulmonic egressive. 

      There is another variety of this pulmonic airstream mechanism. Inhaled air can also be modified to produce speech sounds.  This actually occurs in a few rare and special cases, such as in Tsou, an aboriginal language of Taiwan, which has inhaled [f] and [h] ([h5/˝ps˝] ashes; [f5/tsuju], egg).  Such sounds are called pulmonic ingressive sounds, and the airstream mechanism for making such sounds is called the ingressive rather than the egressive version of the pulmonic airstream mechanism.  Perhaps because it is physiologically harder to slow down an inhalation than an exhalation, pulmonic ingressive sounds are extremely rare.

      The majority of the sounds in all languages of the world are pulmonic egressive sounds.  However, in addition to using air being actively exhaled (or inhaled), two other airstream mechanisms are used to produce some of the sounds in some of the world's languages. 

      1) To understand the second airstream mechanism, the glottalic airstream mechanism, let's first look at a special pulmonic egressive sound, the glottal stop. Air being exhaled from the lungs may be stopped in the throat by a closure of the glottis.  This trapping of air by the glottis is called a glottal stop.  English actually has a glottal stop in certain exclamations:  [u?ow], u?u], [a?a], and in certain dialectical pronunciations: [bottle].  The IPA renders the glottal stop as a question mark without the period. 

      The glottal stop itself is an example of a pulmonic egressive sound, since air from the lungs is being stopped.  However, the glottis can be closed immediately before the production of certain other sounds, trapping a pocket of air in the vocal tract.  If this reservoir of stationary air is then manipulated in the production of a sound it yields another type of airstream mechanism, the glottalic airstream mechanism.  Here's how it works. First, the vocal cords completely close so that for a brief moment no air escapes from the lungs and air is compressed in the throat (pharynx).  

      If the closed glottis is raised to push the air up and outward, an ejective consonant is produced.  The air is forced into the vocal tract and there manipulated by the organs of speech.  Compare glottalized vs. non-glottalized in Georgian.  Ejectives are found in the languages of the Caucasus mountains, among many Native American languages, and among the Afroasiatic languages of north Africa (Hausa, Amharic).

      If the closed glottis is lowered to create a small vacuum in the mouth, an implosive consonant is produced.  The lowering glottis acts like the downward movement of a piston to create a brief rarification of the air in the vocal tract.  When the stricture in the mouth is released air moves into the mouth.  Swahili has three implosives:  [b], [d], [g].  Implosives occur mostly in languages of east Africa, in several Amerindian languages and in some IE languages of northern India.  (Compare the difference between implosives, using the glottalic airstream mechanism, and ingressives, which use inhaled air.)   

      The third and final airstream mechanism used by human language is confined to certain languages of southwest Africa.  It is called the velaric airstream mechanism.  There is regular oral articulation, while the back of tongue seals off air from the lungs and creates a relative vacuum.  Air in the mouth is rarified by backward and downward movement of the tongue.   When the stricture is released the air rushes in, creating a click.  Although we think of such sounds as exotic, English uses a few of them for quasi-linguistic sound gestures:  'grandmother's kiss' (bilabial click), encouraging a horse (lateral click), tisk-tisk (actually a dental or alveolar click).  Some Khoisan languages have over a dozen clicks. (release of click can be supplemented by additional features: aspirated,  nasal/ non-nasal). One Khoisan language  !Xung has 48 different click sounds. A few of the Bantu languages of South Africa, such as Zulu, have clicks; presumably, these sounds were borrowed from the San (Bushmen) and Khoikhoi (Hottentot) peoples who originally lived throughout all southern Africa.   Zulu and the other Bantu languages that use clicks spell them with the letters c, x, q. (cf. the name of the tribe Xhosa).  Notice that clicks stop up the air only in the oral cavity; pulmonic air continues through the nose (one can produce a nasal hum while producing clicks).  

      For the sake of completeness, it should be said that at least one other airstream mechanism could possibly be used for producing sounds in human language.  A puff of air could be trapped in either cheek, then released to be manipulated by the speech organs.  This is the airstream mechanism employed by the Walt Disney character Donand Duck and could be called the buccal airstream mechanism.  So far as we know, Donald Duck is unique in using it. And no language uses a gastric airstream mechanism, which would be modifying air burped up from the stomach.

The phonation process

      The vocal cords can be in one of several positions during the production of a sound.  The muscles of the vocal cords in the glottis can behave in various ways that affect the sound.  The effect of this series of vocal cord states is called the phonation process. 

      Voicing.  Vocal cords can be narrowed along their entire length so that they vibrate as the air passes through them.  All English vowels are voiced.  Voiceless vowels also occur but are far rarer than voiceless consonants are much more common than voiceless vowels.  Voiceless vowels usually occur between voiceless consonants, as in Japanese. No language has only voiceless vowels; a language has either only voiced vowels or voiced and a few voiceless vowels.

        There are also several other vocal cord states that are used to modify sound in the world's languages.  None is used as a regular feature of English.

      Laryngealization.  The posterior (artenoid) portion of the vocal cords can be closed to produce a laryngealized or creaky sound.  This doesn't play a meaningful role in English phonology, althoght we might use a creaky voice to imitate an old witch when reading fairy tales.  Some languages of Southeast Asia and Africa have creaky vowels and consonants, as in Margi, a Nigerian language:  ja to give birth/ laryngealized ja thigh; or in Lango a Nilotic language:  man this/ laryngealized man testicles.

      Murmur.  The anterior (ligamental) portion of the vocal cords can be closed, with the vocal cords vibrating.  This produces murmured or breathy sounds.  Murmured or breathy vowels occur in some languages of Southeast Asia.  We make murmured sounds to imitate the Darth Vader voice.  In many Indo-European languages of India the stop consonants have a murmured release;  in other words the anterior portion of the vocal cords remain closed after the stop has been produced during part of the time the vowel is pronounced:  bh, dh, gh, Buddha.  

      Whisper.  A similar vocal cord state is used to produce the whisper.  The vocal chords are narrowed but not vibrated, narrowing is more complete at the anterior end, less so at the posterior end.  Whispered sounds do not contrast with non-whispered sounds to produce differences of meaning in any known language, but the whispered voice is common as a speech variant across languages.  There is no IPA symbol for a whispered sound.

The oro-nasal process

      Regardless of which airstream mechanism is used, speech sounds are produced when the moving air is somehow obstructed within the vocal tract.  The vocal tract consists of three joined cavities:  the oral cavity, the nasal cavity, and the pharyngeal cavity. The surfaces and boundaries of these cavities are known as the organs of speech.  What happens to the air within these cavities is known as the oro-nasal process. 

      Let's talk first about the oro-nasal process in the articulation, or production, of consonants.

      There are two major ways to classify the activity of the speech organs in the production of consonants:  place of articulation and manner of articulation.

Consonantal place of articulation

      The place of articulation is defined in terms of two articulators These may be: lips, teeth, alveolar ridge, tongue tip (apex), tongue blade (laminus), or back of the tongue (dorsum), hard palate, soft palate (velum), uvula, glottis, pharynx, glottis (the "voice box," or cartilaginous structure where the vocal cords are housed).

bilabial [b, p, m, w]

labiodental, [f, v] [

interdental, [T, D]

(apico)-dental the tip (or apex) of the tongue and the back teeth:  Spanish [t, d, s,].

alveolar (apico-or lamino-) tongue and alveolar ridge (compare 'ten' vs. 'tenth'). Examples:  English [t, d, s, z]

postalveolar or palatoalveolar (apico- or lamino-) (English [S]/[Z]),

retroflex (apico-palatal) bottom of the tongue tip and palate, or alveolar ridge:  Midwest English word-initial [«] and [t, d, n] in many Dravidian languages and many languages of Australia.

palatal (apico- or lamino-) (English [j]),  [S]/[Z] in many languages

velar or dorso-velar Eng. [k, g, N]  German [x]  Greek [V]

uvular French [R], also found in many German dialects.  

pharyngeal (constriction of the sides of the throat), 

glottal (glottal stop, the vocal chords are the two articulators. cf. A-ha, bottle, Cockney English 'ave).  [h] is a glottalic fricative sound.

Manner of articulation

      Now let's look at the ways that moving air can be blocked and modified by various speech organs.  There are several methods of modifying air when producing a consonant, and these methods are called manners of articulation. We have already examined where the air is blocked.  Now let's look at how the air can be blocked.

1) Sounds that completely stop the stream of exhaled air are called plosives:  [d], [t], [b], [p], and [g], [k], glottal stop.  Another word for plosive is stop (nasals are also stops, however, since the air is stopped in the oral cavity during their production).

2) Sound produced by a near complete stoppage of air are called fricatives: [s], [z], [f], [v], [T], [D], [x], [V], [h], pharyngeals.

3) Sometimes a plosive and a fricative will occur together as a single, composite sound called an affricate:  [tS], [ts], [dz], [dZ], [pf]. 

4) All other types of continuant are produced by relatively slight constriction of the oral cavity and are called approximants.  Approximants are those sounds that do not show the same high degree of constriction as fricatives but are more constricted than are vowels. During the production of an approximant, the air flow is smooth rather than turbulent. There are four types of approximants.

a) The glottis is slightly constricted to produce [h], a glottalic approximant.

b) If slight stricture occurs between the roof of the mouth and the tongue a palatal glide is produced [j].  If the constriction is between the two lips, a labiovelar glide is produced.  The glides [j] and [w] are also called semivowels, since they are close to vowels in degree of blockage.

c) If the stricture is in the middle of the mouth, and the air flows out around the sides of the tongue, a lateral is produced.  Laterals, or lateral approximants, are the various l-sounds that occur in language.  In terms of phonetic features, l-sounds are + lateral, while all other sounds are + central.

d) The third type of approximant includes any of the various R-sounds that are not characterized by a flapping or trilling: alveolar and retroflex approximants.  This includes the American English r (symbolized in the IPA by an upside down [®], but we will use the symbol [r]). 

      It the air flow is obstructed only for a brief moment by the touch of the tongue tip against the teeth or alveolar ridge, a tap, or tapped [|] is produced:  cf. Am Engl ladder; British Engl. very. If the tongue tip is actually set in motion by the flow of air so that is vibrates once, a flap or flapped r is produced:  this is the sound of the Spanish single r.  Flaps can even be labio-dental, as in one African language, Margi, spoken in Northern Nigeria.

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