Arabic is a Central Semitic language that first emerged in Iron Age northwestern Arabia and is now the lingua franca of the Arab world. It is named after the Arabs, a term used to describe peoples living in the area bounded by Mesopotamia in the east and the Anti-Lebanon mountains in the west, in northwestern Arabia, in the Sinai Peninsula. Arabic is classified as a macrolanguage comprising 30 modern varieties, including its standard form, Modern Standard Arabic, derived from Classical Arabic; as the modern written language, Modern Standard Arabic is taught in schools and universities, is used to varying degrees in workplaces and the media. The two formal varieties are grouped together as Literary Arabic, the official language of 26 states, the liturgical language of the religion of Islam, since the Quran and Hadith were written in Arabic. Modern Standard Arabic follows the grammatical standards of Classical Arabic, uses much of the same vocabulary. However, it has discarded some grammatical constructions and vocabulary that no longer have any counterpart in the spoken varieties, has adopted certain new constructions and vocabulary from the spoken varieties.
Much of the new vocabulary is used to denote concepts that have arisen in the post-classical era in modern times. Due to its grounding in Classical Arabic, Modern Standard Arabic is removed over a millennium from everyday speech, construed as a multitude of dialects of this language; these dialects and Modern Standard Arabic are described by some scholars as not mutually comprehensible. The former are acquired in families, while the latter is taught in formal education settings. However, there have been studies reporting some degree of comprehension of stories told in the standard variety among preschool-aged children; the relation between Modern Standard Arabic and these dialects is sometimes compared to that of Latin and vernaculars in medieval and early modern Europe. This view though does not take into account the widespread use of Modern Standard Arabic as a medium of audiovisual communication in today's mass media—a function Latin has never performed. During the Middle Ages, Literary Arabic was a major vehicle of culture in Europe in science and philosophy.
As a result, many European languages have borrowed many words from it. Arabic influence in vocabulary, is seen in European languages Spanish and to a lesser extent Portuguese, Catalan, owing to both the proximity of Christian European and Muslim Arab civilizations and 800 years of Arabic culture and language in the Iberian Peninsula, referred to in Arabic as al-Andalus. Sicilian has about 500 Arabic words as result of Sicily being progressively conquered by Arabs from North Africa, from the mid-9th to mid-10th centuries. Many of these words relate to related activities; the Balkan languages, including Greek and Bulgarian, have acquired a significant number of Arabic words through contact with Ottoman Turkish. Arabic has influenced many languages around the globe throughout its history; some of the most influenced languages are Persian, Spanish, Kashmiri, Bosnian, Bengali, Malay, Indonesian, Punjabi, Assamese, Sindhi and Hausa, some languages in parts of Africa. Conversely, Arabic has borrowed words from other languages, including Greek and Persian in medieval times, contemporary European languages such as English and French in modern times.
Classical Arabic is the liturgical language of 1.8 billion Muslims, Modern Standard Arabic is one of six official languages of the United Nations. All varieties of Arabic combined are spoken by as many as 422 million speakers in the Arab world, making it the fifth most spoken language in the world. Arabic is written with the Arabic alphabet, an abjad script and is written from right to left, although the spoken varieties are sometimes written in ASCII Latin from left to right with no standardized orthography. Arabic is a Central Semitic language related to the Northwest Semitic languages, the Ancient South Arabian languages, various other Semitic languages of Arabia such as Dadanitic; the Semitic languages changed a great deal between Proto-Semitic and the establishment of the Central Semitic languages in grammar. Innovations of the Central Semitic languages—all maintained in Arabic—include: The conversion of the suffix-conjugated stative formation into a past tense; the conversion of the prefix-conjugated preterite-tense formation into a present tense.
The elimination of other prefix-conjugated mood/aspect forms in favor of new moods formed by endings attached to the prefix-conjugation forms. The development of an internal passive. There are several features which Classical Arabic, the modern Arabic varieties, as well as the Safaitic and Hismaic inscriptions share which are unattested in any other Central Semitic language variety, including the Dadanitic and Taymanitic languages of the northern Hejaz; these features are evidence of common descent from Proto-Arabic. The following features can be reconstructed with confidence for Proto-Arabic: negative particles m *mā.
The Albanian alphabet is a variant of the Latin alphabet used to write the Albanian language. It consists of 36 letters: Note: The vowels are shown in bold. Listen to the pronunciation of the 36 letters; the earliest known mention of Albanian writings comes from a French Catholic church document from 1332. Written either by archbishop Guillaume Adam or the monk Brocardus Monacus the report notes that Licet Albanenses aliam omnino linguam a latina habeant et diversam, tamen litteram latinam habent in uso et in omnibus suis libris. Scholars warn that this could mean Albanians wrote in the Latin language, not just Albanian with a Latin script; the history of the Albanian alphabet is linked with the influence of religion among Albanians. The writers from the North of Albania used Latin letters under the influence of the Catholic Church, those from the South of Albania under the Greek Orthodox church used Greek letters, while others used Arabic letters under the influence of Islam. There were attempts for an original Albanian alphabet in the period of 1750–1850.
The current alphabet in use among Albanians is one of the two variants approved in the Congress of Monastir held by Albanian intellectuals from November 14 to 22 November 1908, in Monastir. A first reference for Latin letters was in a medieval Latin manuscript of 1332 attributed to a monk called Brocardus Monacus or to one Guillaume Adam. In this manuscript there is a quoted phrase about the existence of books in Albania "licet Albanenses aliam omnino linguam a latina habeant et diversam, tamen litteram latinam habent in usu et in omnibus suis libris"; the earliest document discovered so far, written in Albanian is a manuscript from 1210 by Theodor of Shkodra written in Latin characters. The first certain document in Albanian "Formula e pagëzimit", issued by Pal Engjëlli, was written in Latin characters, it was a simple phrase, supposed to be used by the relatives of a dying person if they couldn't make it to churches during the troubled times of the Ottoman invasion. The five Albanian writers of the 16th and 17th centuries who form the core of early Albanian literature, all used a Latin alphabet for their Albanian books.
The Greek intellectual Anastasios Michael, in his speech to the Berlin Academy mentions an Albanian alphabet produced "recently" by Kosmas from Cyprus, bishop of Dyrrachium. It is assumed that this is the alphabet used for the "Gospel of Elbasan". Anastasios calls Kosmas the "Cadmus of Albania". In 1857 Kostandin Kristoforidhi, an Albanian scholar and translator, drafted in Istanbul, Ottoman Empire, a Memorandum for the Albanian language', he went to Malta, where he stayed until 1860 in a Protestant seminary, finishing the translation of The New Testament in the Tosk and Gheg dialects. He was helped by Nikolla Serreqi from Shkodër with the Gheg version of the Testament. Nikolla Serreqi was the propulsor for the use of the Latin script for the translation of the New Testament, used by the early writers of the Albanian literature and Kristoforidhi enthusiastically embraced the idea of a Latin alphabet. In November 1869, a Commission for the Alphabet of the Albanian Language was gathered in Istanbul.
One of its members was Kostandin Kristoforidhi and the main purpose of the Commission was the creation of a unique alphabet for all the Albanians. In January 1870 the Commission ended its work of the standardization of the alphabet, in Latin letters. A plan on the creation of textbooks and spread of Albanian schools was drafted; however this plan was not realized, because the Ottoman Government wouldn't finance the expenses for the establishment of such schools. Although this commission had gathered and delivered an alphabet in 1870, the writers from the North still used the Latin-based alphabet, whereas in Southern Albania writers used the Greek letters. In Southern Albania, the main activity of Albanian writers consisted in translating Greek Orthodox religious text and not in forming any kind of literature which could form a strong tradition for the use of Greek letters; as the Albanologist Robert Elsie has written: The predominance of Greek as the language of Christian education and culture in southern Albania and the hostile attitude of the Orthodox church to the spread of writing in Albanian made it impossible for an Albanian literature in Greek script to evolve.
The Orthodox church, as the main vehicle of culture in the southern Balkans, while intent on spreading Christian education and values, was never convinced of the utility of writing in the vernacular as a means of converting the masses, as the Catholic church in northern Albania had been, to a certain extent, during the Counter-Reformation. Nor, with the exception of the ephemeral printing press in Voskopoja, did the southern Albanians have at their disposal publishing facilities like those available to the clerics and scholars of Catholic Albania in Venice and Dalmatia; as such, the Orthodox tradition in Albanian writing, a strong cultural heritage of scholarship and erudition, though one limited to translations of religious texts and to the compilation of dictionaries, was to remain a flower which never blossomed. The turning
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between those layers. Turbulence is observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason turbulence is realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other drag due to friction effects increases; this increases the energy needed to pump fluid through a pipe. Turbulence can be exploited, for example, by devices such as aerodynamic spoilers on aircraft that "spoil" the laminar flow to increase drag and reduce lift.
The onset of turbulence can be predicted by the dimensionless Reynolds number, the ratio of kinetic energy to viscous damping in a fluid flow. However, turbulence has long resisted detailed physical analysis, the interactions within turbulence create a complex phenomenon. Richard Feynman has described turbulence as the most important unsolved problem in classical physics. Smoke rising from a cigarette. For the first few centimeters, the smoke is laminar; the smoke plume becomes turbulent as its Reynolds number increases with increases in flow velocity and characteristic lengthscale. Flow over a golf ball. If the golf ball were smooth, the boundary layer flow over the front of the sphere would be laminar at typical conditions. However, the boundary layer would separate early, as the pressure gradient switched from favorable to unfavorable, creating a large region of low pressure behind the ball that creates high form drag. To prevent this, the surface is dimpled to promote turbulence; this results in higher skin friction, but it moves the point of boundary layer separation further along, resulting in lower drag.
Clear-air turbulence experienced during airplane flight, as well as poor astronomical seeing. Most of the terrestrial atmospheric circulation; the oceanic and atmospheric mixed intense oceanic currents. The flow conditions in many industrial equipment and machines; the external flow over all kinds of vehicles such as cars, airplanes and submarines. The motions of matter in stellar atmospheres. A jet exhausting from a nozzle into a quiescent fluid; as the flow emerges into this external fluid, shear layers originating at the lips of the nozzle are created. These layers separate the fast moving jet from the external fluid, at a certain critical Reynolds number they become unstable and break down to turbulence. Biologically generated. Snow fences work by inducing turbulence in the wind, forcing it to drop much of its snow load near the fence. Bridge supports in water. In the late summer and fall, when river flow is slow, water flows smoothly around the support legs. In the spring, when the flow is faster, a higher Reynolds number is associated with the flow.
The flow may start off laminar but is separated from the leg and becomes turbulent. In many geophysical flows, the flow turbulence is dominated by the coherent structures and turbulent events. A turbulent event is a series of turbulent fluctuations that contain more energy than the average flow turbulence; the turbulent events are associated with coherent flow structures such as eddies and turbulent bursting, they play a critical role in terms of sediment scour and transport in rivers as well as contaminant mixing and dispersion in rivers and estuaries, in the atmosphere. In the medical field of cardiology, a stethoscope is used to detect heart sounds and bruits, which are due to turbulent blood flow. In normal individuals, heart sounds are a product of turbulent flow as heart valves close. However, in some conditions turbulent flow can be audible due to other reasons, some of them pathological. For example, in advanced atherosclerosis, bruits can be heard in some vessels that have been narrowed by the disease process.
Turbulence in porous media became a debated subject. Turbulence is characterized by the following features: Irregularity Turbulent flows are always irregular. For this reason, turbulence problems are treated statistically rather than deterministically. Turbulent flow is chaotic. However, not all chaotic flows are turbulent. Diffusivity The available supply of energy in turbulent flows tends to accelerate the homogenization of fluid mixtures; the characteristic, responsible for the enhanced mixing and increased rates of mass and energy transports in a flow is called "diffusivity". Turbulent diffusion is described by a turbulent diffusion coefficient; this turbulent diffusion coefficient is defined in a phenomenological sense, by analogy with the molecular diffusivities, but it does not have a true physical meaning, being dependent on the flow conditions, not a property of the fluid itself. In addition, the turbulent diffusivity concept assumes a con
Labialization is a secondary articulatory feature of sounds in some languages. Labialized sounds involve the lips; the term is restricted to consonants. When vowels involve the lips, they are called rounded; the most common labialized consonants are labialized velars. Most other labialized sounds have simultaneous velarization, the process may be more called labio-velarization. In phonology, labialization may refer to a type of assimilation process. Labialization is the most widespread secondary articulation in the world's languages, it is phonemically contrastive in Northwest Caucasian and Salishan language families, among others. This contrast is reconstructed for Proto-Indo-European, the common ancestor of the Indo-European languages. American English has three degrees of labialization: tight rounded, slight rounded, unrounded, which in vowels is sometimes called'spread'; these secondary articulations are not universal. For example, French shares the English slight rounding of /ʃ/, /ʒ/ while Russian does not have slight rounding in its postalveolar fricatives.
A few languages, including Arrernte and Mba, have contrastive labialized forms for all of their consonants. Out of 706 language inventories surveyed by Ruhlen, labialization occurred most with velar and uvular segments and least with dental and alveolar segments. With non-dorsal consonants, labialization may include velarization as well. Labialization is not restricted to lip-rounding; the following articulations have either been described as labialization, or been found as allophonic realizations of prototypical labialization: Labiodental frication, found in Abkhaz Complete bilabial closure, found in Abkhaz and Ubykh "Labialization" without noticeable rounding of the lips, found in the Iroquoian languages. It may be. Rounding without velarization, found in Shona and in the Bzyb dialect of Abkhaz. Eastern Arrernte has labialization at all manners of articulation. Marshallese has labialization at all places of articulation except for coronal obstruents. In North America, languages from a number of families have sounds that sound labialized without participation of the lips.
See Tillamook language for an example. In the International Phonetic Alphabet, labialization of velar consonants is indicated with a raised w modifier, as in /kʷ/. There are diacritics to indicate greater or lesser degrees of rounding; these are used with vowels, but may occur with consonants. For example, in the Athabaskan language Hupa, voiceless velar fricatives distinguish three degrees of labialization, transcribed either /x/, /x̹/, /xʷ/ or /x/, /x̜ʷ/, /xʷ/; the extensions to the IPA has two additional symbols for degrees of rounding: Spread and open-rounded. It has a symbol for labiodentalized sounds. If precision is desired, the Abkhaz and Ubykh articulations may be transcribed with the appropriate fricative or trill raised as a diacritic:. For simple labialization, Ladefoged & Maddieson resurrected an old IPA symbol, which would be placed above a letter with a descender such as ɡ. However, their chief example is Shona sv and zv, which they transcribe /s̫/ and /z̫/ but which seem to be whistled sibilants, without being labialized.
Another possibility is to use the IPA diacritic for rounding, distinguishing for example the labialization in English soon and swoon. The open rounding of English /ʃ/ is unvelarized. Labialization refers to a specific type of assimilatory process where a given sound become labialized due to the influence of neighboring labial sounds. For example, /k/ may become /kʷ/ in the environment of /o/, or /a/ may become /o/ in the environment of /p/ or /kʷ/. In the Northwest Caucasian languages as well as some Australian languages rounding has shifted from the vowels to the consonants, producing a wide range of labialized consonants and leaving in some cases only two phonemic vowels; this appears to have been the case in Eastern Arrernte, for example. The labial vowel sounds still remain, but only as allophones next to the now-labial consonant sounds. Labialized voiceless alveolar stop labialized voiced alveolar stop labialized voiceless velar stop labialized voiced velar stop ( labialized voiceless uvular stop ( labialized pharyngealized voiceless uvular stop labialized voiced uvular stop ( labialized glottal stop ( labialized voiceless bilabial stop ( labialized voiced bilabial stop ( labialized prenasalized voiced bilabial plosive (in Tamamb
International Phonetic Alphabet
The International Phonetic Alphabet is an alphabetic system of phonetic notation based on the Latin alphabet. It was devised by the International Phonetic Association in the late 19th century as a standardized representation of the sounds of spoken language; the IPA is used by lexicographers, foreign language students and teachers, speech-language pathologists, actors, constructed language creators and translators. The IPA is designed to represent only those qualities of speech that are part of oral language: phones, phonemes and the separation of words and syllables. To represent additional qualities of speech, such as tooth gnashing and sounds made with a cleft lip and cleft palate, an extended set of symbols, the extensions to the International Phonetic Alphabet, may be used. IPA symbols are composed of one or more elements of two basic types and diacritics. For example, the sound of the English letter ⟨t⟩ may be transcribed in IPA with a single letter, or with a letter plus diacritics, depending on how precise one wishes to be.
Slashes are used to signal broad or phonemic transcription. Letters or diacritics are added, removed or modified by the International Phonetic Association; as of the most recent change in 2005, there are 107 letters, 52 diacritics and four prosodic marks in the IPA. These are shown in the current IPA chart, posted below in this article and at the website of the IPA. In 1886, a group of French and British language teachers, led by the French linguist Paul Passy, formed what would come to be known from 1897 onwards as the International Phonetic Association, their original alphabet was based on a spelling reform for English known as the Romic alphabet, but in order to make it usable for other languages, the values of the symbols were allowed to vary from language to language. For example, the sound was represented with the letter ⟨c⟩ in English, but with the digraph ⟨ch⟩ in French. However, in 1888, the alphabet was revised so as to be uniform across languages, thus providing the base for all future revisions.
The idea of making the IPA was first suggested by Otto Jespersen in a letter to Paul Passy. It was developed by Alexander John Ellis, Henry Sweet, Daniel Jones, Passy. Since its creation, the IPA has undergone a number of revisions. After revisions and expansions from the 1890s to the 1940s, the IPA remained unchanged until the Kiel Convention in 1989. A minor revision took place in 1993 with the addition of four letters for mid central vowels and the removal of letters for voiceless implosives; the alphabet was last revised in May 2005 with the addition of a letter for a labiodental flap. Apart from the addition and removal of symbols, changes to the IPA have consisted of renaming symbols and categories and in modifying typefaces. Extensions to the International Phonetic Alphabet for speech pathology were created in 1990 and adopted by the International Clinical Phonetics and Linguistics Association in 1994; the general principle of the IPA is to provide one letter for each distinctive sound, although this practice is not followed if the sound itself is complex.
This means that: It does not use combinations of letters to represent single sounds, the way English does with ⟨sh⟩, ⟨th⟩ and ⟨ng⟩, or single letters to represent multiple sounds the way ⟨x⟩ represents /ks/ or /ɡz/ in English. There are no letters that have context-dependent sound values, as do "hard" and "soft" ⟨c⟩ or ⟨g⟩ in several European languages; the IPA does not have separate letters for two sounds if no known language makes a distinction between them, a property known as "selectiveness". Among the symbols of the IPA, 107 letters represent consonants and vowels, 31 diacritics are used to modify these, 19 additional signs indicate suprasegmental qualities such as length, tone and intonation; these are organized into a chart. The letters chosen for the IPA are meant to harmonize with the Latin alphabet. For this reason, most letters modifications thereof; some letters are neither: for example, the letter denoting the glottal stop, ⟨ʔ⟩, has the form of a dotless question mark, derives from an apostrophe.
A few letters, such as that of the voiced pharyngeal fricative, ⟨ʕ⟩, were inspired by other writing systems. Despite its preference for harmonizing with the Latin script, the International Phonetic Association has admitted other letters. For example, before 1989, the IPA letters for click consonants were ⟨ʘ⟩, ⟨ʇ⟩, ⟨ʗ⟩, ⟨ʖ⟩, all of which were derived either from existing IPA letters, or from Latin and Greek letters. However, except for ⟨ʘ⟩, none of these letters were used among Khoisanists or Bantuists, as a result they were replaced by the more widespread symbols ⟨ʘ⟩, ⟨ǀ⟩, ⟨ǃ⟩, ⟨ǂ⟩, ⟨ǁ⟩ at the IPA Kiel Convention in 1989. Although the IPA diacritics are featural, there is little systemicity in the letter forms. A retroflex articulation is indicated with a right-swinging tail, as in ⟨ɖ ʂ ɳ⟩, implosion by a top hook, ⟨ɓ ɗ ɠ⟩, but other pseudo-featural elements are due to haphazard derivation and coincidence. For example, all nasal consonants but uvular ⟨ɴ⟩ are based on the form ⟨n⟩: ⟨m ɱ n ɳ ɲ ŋ⟩.
However, the similarity between ⟨m⟩ and ⟨n⟩ is a historical accident. Some of the new letters were ordinary Latin letters tu
The term phonation has different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration; this is the definition used among those who study laryngeal anatomy and physiology and speech production in general. Phoneticians in other subfields, such as linguistic phonetics, call this process voicing, use the term phonation to refer to any oscillatory state of any part of the larynx that modifies the airstream, of which voicing is just one example. Voiceless and supra-glottal phonations are included under this definition; the phonatory process, or voicing, occurs when air is expelled from the lungs through the glottis, creating a pressure drop across the larynx. When this drop becomes sufficiently large, the vocal folds start to oscillate; the minimum pressure drop required to achieve phonation is called the phonation threshold pressure, for humans with normal vocal folds, it is 2–3 cm H2O.
The motion of the vocal folds during oscillation is lateral, though there is some superior component as well. However, there is no motion along the length of the vocal folds; the oscillation of the vocal folds serves to modulate the pressure and flow of the air through the larynx, this modulated airflow is the main component of the sound of most voiced phones. The sound that the larynx produces is a harmonic series. In other words, it consists of a fundamental tone accompanied by harmonic overtones, which are multiples of the fundamental frequency. According to the source–filter theory, the resulting sound excites the resonance chamber, the vocal tract to produce the individual speech sounds; the vocal folds will not oscillate if they are not sufficiently close to one another, are not under sufficient tension or under too much tension, or if the pressure drop across the larynx is not sufficiently large. In linguistics, a phone is called voiceless. In speech, voiceless phones are associated with vocal folds that are elongated tensed, placed laterally when compared to vocal folds during phonation.
Fundamental frequency, the main acoustic cue for the percept pitch, can be varied through a variety of means. Large scale changes are accomplished by increasing the tension in the vocal folds through contraction of the cricothyroid muscle. Smaller changes in tension can be effected by contraction of the thyroarytenoid muscle or changes in the relative position of the thyroid and cricoid cartilages, as may occur when the larynx is lowered or raised, either volitionally or through movement of the tongue to which the larynx is attached via the hyoid bone. In addition to tension changes, fundamental frequency is affected by the pressure drop across the larynx, affected by the pressure in the lungs, will vary with the distance between the vocal folds. Variation in fundamental frequency is used linguistically to produce tone. There are two main theories as to how vibration of the vocal folds is initiated: the myoelastic theory and the aerodynamic theory; these two theories are not in contention with one another and it is quite possible that both theories are true and operating to initiate and maintain vibration.
A third theory, the neurochronaxic theory, was in considerable vogue in the 1950s, but has since been discredited. The myoelastic theory states that when the vocal cords are brought together and breath pressure is applied to them, the cords remain closed until the pressure beneath them, the subglottic pressure, is sufficient to push them apart, allowing air to escape and reducing the pressure enough for the muscle tension recoil to pull the folds back together again; the pressure builds up once again until the cords are pushed apart, the whole cycle keeps repeating itself. The rate at which the cords open and close, the number of cycles per second, determines the pitch of the phonation; the aerodynamic theory is based on the Bernoulli energy law in fluids. The theory states that when a stream of breath is flowing through the glottis while the arytenoid cartilages are held together, a push-pull effect is created on the vocal fold tissues that maintains self-sustained oscillation; the push occurs during glottal opening, when the glottis is convergent, the pull occurs during glottal closing, when the glottis is divergent.
Such an effect causes a transfer of energy from the airflow to the vocal fold tissues which overcomes losses by dissipation and sustain the oscillation. The amount of lung pressure needed to begin phonation is defined by Titze as the oscillation threshold pressure. During glottal closure, the air flow is cut off until breath pressure pushes the folds apart and the flow starts up again, causing the cycles to repeat; the textbook entitled Myoelastic Aerodynamic Theory of Phonation by Ingo Titze credits Janwillem van den Berg as the originator of the theory and provides detailed mathematical development of the theory. This theory states that the frequency of the vocal fold vibration is determined by the chronaxie of the recurrent nerve, not by breath pressure or muscular tension. Advocates of this theory thought that every single vibration of the vocal folds was due to an impulse from the recurrent laryngeal nerves and that the acoustic center in the brain regulated the speed of vocal fold vibration.
Speech and voice scientists have long since left this theory as the muscles have been shown to not be able to contract fast enough to accomplish the vibration. In addition, persons with paralyzed vocal folds can produce phonation, whic
Manner of articulation
In articulatory phonetics, the manner of articulation is the configuration and interaction of the articulators when making a speech sound. One parameter of manner is stricture, that is, how the speech organs approach one another. Others include those involved in the r-like sounds, the sibilancy of fricatives; the concept of manner is used in the discussion of consonants, although the movement of the articulators will greatly alter the resonant properties of the vocal tract, thereby changing the formant structure of speech sounds, crucial for the identification of vowels. For consonants, the place of articulation and the degree of phonation of voicing are considered separately from manner, as being independent parameters. Homorganic consonants, which have the same place of articulation, may have different manners of articulation. Nasality and laterality are included in manner, but some phoneticians, such as Peter Ladefoged, consider them to be independent. Manners of articulation with substantial obstruction of the airflow are called obstruents.
These are prototypically voiceless, but voiced obstruents are common as well. Manners without such obstruction are called sonorants. Voiceless sonorants are uncommon, but are found in Welsh and Classical Greek, in Standard Tibetan, the "wh" in those dialects of English that distinguish "which" from "witch". Sonorants may be called resonants, some linguists prefer that term, restricting the word'sonorant' to non-vocoid resonants. Another common distinction is between continuants. From greatest to least stricture, speech sounds may be classified along a cline as stop consonants, fricative consonants and vowels. Affricates behave as if they were intermediate between stops and fricatives, but phonetically they are sequences of a stop and fricative. Over time, sounds in a language may move along this cline toward less stricture in a process called lenition, or towards more stricture in a process called fortition. Sibilants are distinguished from other fricatives by the shape of the tongue and how the airflow is directed over the teeth.
Fricatives at coronal places of articulation may be sibilant or non-sibilant, sibilants being the more common. Flaps are similar to brief stops. However, their articulation and behavior are distinct enough to be considered a separate manner, rather than just length; the main articulatory difference between flaps and stops is that, due to the greater length of stops compared to flaps, a build-up of air pressure occurs behind a stop which does not occur behind a flap. This means that when the stop is released, there is a burst of air as the pressure is relieved, while for flaps there is no such burst. Trills involve the vibration of one of the speech organs. Since trilling is a separate parameter from stricture, the two may be combined. Increasing the stricture of a typical trill results in a trilled fricative. Trilled affricates are known. Nasal airflow may be added as an independent parameter to any speech sound, it is most found in nasal occlusives and nasal vowels, but nasalized fricatives and approximants are found.
When a sound is not nasal, it is called oral. Laterality is the release of airflow at the side of the tongue; this can be combined with other manners, resulting in lateral approximants, lateral flaps, lateral fricatives and affricates. Stop, an oral occlusive, where there is occlusion of the oral vocal tract, no nasal air flow, so the air flow stops completely. Examples include English /p t k/ and /b d ɡ/. If the consonant is voiced, the voicing is the only sound made during occlusion. What we hear as a /p/ or /k/ is the effect that the onset of the occlusion has on the preceding vowel, as well as the release burst and its effect on the following vowel; the shape and position of the tongue determine the resonant cavity that gives different stops their characteristic sounds. All languages have stops. Nasal, a nasal occlusive, where there is occlusion of the oral tract, but air passes through the nose; the shape and position of the tongue determine the resonant cavity that gives different nasals their characteristic sounds.
Examples include English /m, n/. Nearly all languages have nasals, the only exceptions being in the area of Puget Sound and a single language on Bougainville Island. Fricative, sometimes called spirant, where there is continuous frication at the place of articulation. Examples include etc.. Most languages have fricatives, though many have only an /s/. However, the Indigenous Australian languages are completely devoid of fricatives of any kind. Sibilants are a type of fricative where the airflow is guided by a groove in the tongue toward the teeth, creating a high-pitched and distinctive sound; these are by far the most common fricatives. Fricatives at coronal places of articulation are though not always, sibilants. English sibilants include /s/ and /z/. Lateral fricatives are a rare type of fricative, where the frication occurs on one or both sides of the edge of th