The Syriac alphabet is a writing system used to write the Syriac language since the 1st century AD. It is one of the Semitic abjads descending from the Aramaic alphabet through the Palmyrene alphabet, shares similarities with the Phoenician, Hebrew and the traditional Mongolian scripts. Syriac is written from right to left in horizontal lines, it is a cursive script where not all, letters connect within a word. Spaces separate individual words. All 22 letters are consonants, although there are optional diacritic marks to indicate vowels and other features. In addition to the sounds of the language, the letters of the Syriac alphabet can be used to represent numbers in a system similar to Hebrew and Greek numerals. Apart from Classical Syriac Aramaic, the alphabet has been used to write other dialects and languages. Several Christian Neo-Aramaic languages from Turoyo to the Northeastern Neo-Aramaic dialects of Assyrian and Chaldean, once vernaculars began to be written in the 19th century; the Serṭā variant has been adapted to write Western Neo-Aramaic, traditionally written in a square Aramaic script related to the Hebrew alphabet.
Besides Aramaic, when Arabic began to be the dominant spoken language in the Fertile Crescent after the Islamic conquest, texts were written in Arabic using the Syriac script as knowledge of the Arabic alphabet was not yet widespread. Such writings are called Karshuni or Garshuni. In addition to Semitic languages, Malayalam was written with Syriac script and was called Suriyani Malayalam, as well as Sogdian. There are three major variants of the Syriac alphabet: ʾEsṭrangēlā, Maḏnḥāyā and Serṭā; the oldest and classical form of the alphabet is ʾEsṭrangēlā. Although ʾEsṭrangēlā is no longer used as the main script for writing Syriac, it has received some revival since the 10th century, it is used in scholarly publications, in titles, in inscriptions. In some older manuscripts and inscriptions, it is possible for any letter to join to the left, older Aramaic letter forms are found. Vowel marks are not used with ʾEsṭrangēlā; the East Syriac dialect is written in the Maḏnḥāyā form of the alphabet. Other names for the script include Swāḏāyā, ʾĀṯūrāyā, Kaldāyā, inaccurately, "Nestorian".
The Eastern script resembles ʾEsṭrangēlā somewhat more than the Western script. The Eastern script uses a system of dots above or below letters, based on an older system, to indicate vowel sounds not found in the script: A dot above and a dot below a letter represent, transliterated as a or ă, Two diagonally-placed dots above a letter represent, transliterated as ā or â or å, Two horizontally-placed dots below a letter represent, transliterated as e or ĕ, Two diagonally-placed dots below a letter represent, transliterated as ē, The letter Waw with a dot below it represents, transliterated as ū or u, The letter Waw with a dot above it represents, transliterated as ō or o, The letter Yōḏ with a dot beneath it represents, transliterated as ī or i, A combination of Rḇāṣā karyā followed by a letter Yōḏ represents, transliterated as ē or ê, it is thought that the Eastern method for representing vowels influenced the development of the niqqud markings used for writing Hebrew. In addition to the above vowel marks, transliteration of Syriac sometimes includes ə, e̊ or superscript e to represent an original Aramaic schwa that became lost on at some point in the development of Syriac.
Some transliteration schemes find its inclusion necessary for showing spirantization or for historical reasons. Whether because its distribution is predictable or because its pronunciation was lost, both the East and the West variants of the alphabet have no sign to represent the schwa; the West Syriac dialect is written in the Serṭā or Serṭo form of the alphabet known as the Pšīṭā,'Maronite' or the'Jacobite' script. Most of the letters are derived from ʾEsṭrangēlā, but are simplified, flowing lines. A cursive chancery hand is evidenced in the earliest Syriac manuscripts, but important works were written in ʾEsṭrangēlā. From the 8th century, the simpler Serṭā style came into fashion because of its more economical use of parchment; the Western script is vowel-pointed, with miniature Greek vowel letters above or below the letter which they follow: Capital Alpha represents, transliterated as a or ă, Lowercase Alpha represents, transliterated as
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.
Assyrian Neo-Aramaic or Assyrian known as Eastern Syriac, is a Neo-Aramaic language within the Semitic branch of the Afro-Asiatic language family, spoken by Assyrian people. The various Assyrian Aramaic dialects, including Assyrian Neo-Aramaic, have been influenced by--though not directly descended from--Classical Syriac, the Middle Aramaic dialect of Edessa, after its adoption as an official liturgical language, they are also descended from Old Aramaic, the lingua franca in the phase of the Neo-Assyrian Empire, displacing the East Semitic Assyrian dialect of Akkadian beginning around the 10th century BC. Assyrian Neo-Aramaic is spoken by an estimated 200,000 people who are native to Upper Mesopotamia, a large region stretching from the plain of Urmia in northwestern Iran to the Nineveh plains, the Erbil and Duhok regions in northern Iraq, together with the Al-Hasakah region of northeastern Syria, parts of southeastern Turkey. Instability throughout the Middle East over the past century has led to a worldwide diaspora of Assyrian speakers, with many speakers now living abroad in such places as North America and Europe.
Speakers of Assyrian Neo-Aramaic, Chaldean Neo-Aramaic and Turoyo are ethnic Assyrians and are descendants of the ancient Assyrian inhabitants of Northern Mesopotamia. Assyrian Neo-Aramaic is one of the largest Neo-Aramaic languages, with Chaldean Neo-Aramaic and Turoyo making up most of the remaining Neo-Aramaic speakers. Despite the terms "Chaldean Neo-Aramaic" and "Assyrian Neo-Aramaic" indicating a separate ethnoreligious identity, both the languages and their native speakers originate from the same Upper Mesopotamian region. Nonetheless, all these languages evolve from Aramaic, which was, along with Latin and Greek, one of "the three most important Christian languages in the early centuries" of the Common Era. Assyrian Neo-Aramaic is, to a significant degree, mutually intelligible with Chaldean Neo-Aramaic and they are sometimes considered to constitute dialects of the same language rather than two separate languages. To a moderate degree, Assyrian is intelligible with Senaya, Lishana Deni and Bohtan Neo-Aramaic, is intelligible with Lishan Didan, Hulaulá and Lishanid Noshan.
Its mutual intelligibility with Turoyo, a Central Neo-Aramaic language, is partial and asymmetrical, but more significant in written form. Evolved in the 13th century from Middle Aramaic, Assyrian Neo-Aramaic is a moderately-inflected, fusional language with a two-gender noun system and rather flexible word order. There is some Akkadian influence in the language. In its native region, speakers may use Iranian and Arabic loanwords, while diaspora communities may use loanwords borrowed from the languages of their respective countries. Assyrian Neo-Aramaic is written from right-to-left and it uses the Madnhāyā version of the Syriac alphabet. Assyrian, alongside other modern Aramaic languages, is now considered endangered. Aramaic was the language of commerce and communication and became the vernacular language of Assyria in the late Iron Age and classical antiquity, it became the lingua franca of the Neo-Assyrian Empire, Neo-Babylonian Empire, the Achaemenid Empire, the Parthian Empire, the Sasanian Empire.
Aramaic writing has been found as far north as Hadrians Wall in Ancient Britain, in the form of inscriptions in Aramaic, made by Assyrian and Aramean soldiers serving in the Roman Legions in northern England during the 2nd century AD. The Assyrian Empire resorted to a policy of deporting troublesome conquered peoples into the lands of Mesopotamia. By the 6th century, the indigenous and Akkadian-speaking Semites of Assyria and Babylonia, spoke Akkadian-infused dialects of Eastern Aramaic. During the Persian rule of Assyria, Aramaic became the main language spoken by the Assyrians. Before the Empire fell, Aramaic had become the lingua franca of its empire and Assyrians were capable of speaking both Akkadian and Aramaic. Local unwritten Aramaic dialects emerged from Imperial Aramaic in Assyria–northern Mesopotamia, an Akkadian-influenced version of the Old Aramaic language, introduced as the lingua franca of the Neo-Assyrian Empire by Tiglath-Pileser III; the first evidence of such dialects emerged in Assyria, begin to influence the written Imperial Aramaic from the 5th century BC.
Following the Achaemenid conquest of Assyria under Darius I, the Aramaic language was adopted as the "vehicle for written communication between the different regions of the vast empire with its different peoples and languages". After the conquest of Assyria by the Seleucid Empire in the late 4th century BC, Imperial Aramaic and other Aramaic dialects lost their status as imperial languages but continued to flourish as lingua francas alongside Ancient Greek. By the 1st century AD, Akkadian was extinct, although some loaned vocabulary and grammatical features still survives in Assyrian Neo-Aramaic and other Assyrian languages to this day; the Neo-Aramaic languages evolved from Middle Aramaic by the 13th century. There is evidence. Much literary effort was put into the production of an authoritative translation of the Bible into Syriac, the Peshitta. At the same time, Ephrem the Syrian was producing the most treasured collection of poetry and theology in the Classical Syriac language. By the 3rd century AD, churches in Edessa in the kingdom
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
While many languages have numerous dialects that differ in phonology, the contemporary spoken Arabic language is more properly described as a continuum of varieties. This article deals with Modern Standard Arabic, the standard variety shared by educated speakers throughout Arabic-speaking regions. MSA is used in writing in formal print media and orally in newscasts and formal declarations of numerous types. Modern Standard Arabic has 6 vowel phonemes. All phonemes contrast between non-emphatic ones; some of these phonemes have coalesced in the various modern dialects, while new phonemes have been introduced through borrowing or phonemic splits. A "phonemic quality of length" applies to consonants as well as vowels. Modern Standard Arabic has six vowel phonemes forming three pairs of corresponding short and long vowels. Many spoken varieties include /oː/ and /eː/. Modern Standard Arabic has two diphthongs in Classical Arabic with no allophones. Allophony in different dialects of Arabic can occur, is conditioned by neighboring consonants within the same word.
As a general rule, for example, /a/ and /aː/ are: /a, aː/ retracted to in the environment of a neighboring /r/, /q/ or an emphatic consonant: /sˤ/, /dˤ/, /tˤ/, /ðˤ/, /ɫ/ and in a few regional standard pronunciations /x/ and /ɣ/. /i, iː, u, uː/ Across North Africa and West Asia, /i/ may be realized as before or adjacent to emphatic consonants and. /u/ can have different realizations, i.e.. Sometimes with one value for each vowel in both short and long lengths or two different values for each short and long lengths, they are distinct phonemes in loan words. In Egypt, close vowels have different values. /i~ɪ/ and /u~ʊ/ become and in some other particular dialects. Unstressed final long /aː, iː, uː/ are most shortened or reduced: /aː/ →, /iː/ →, /uː/ →. However, the actual rules governing vowel-retraction are a good deal more complex, have little in the way of an agreed-upon standard, as there are competing notions of what constitutes a "prestige" form. Highly proficient speakers will import the vowel-retraction rules from their native dialects.
Thus, for example, in the Arabic of someone from Cairo emphatic consonants will affect every vowel between word boundaries, whereas certain Saudi speakers exhibit emphasis only on the vowels adjacent to an emphatic consonant. Certain speakers exhibit a degree of asymmetry in leftward vs. rightward spread of vowel-retraction. The final heavy syllable of a root is stressed. However, the pronunciation of loanwords is dependent on the speaker's native variety; the long mid vowels /oː/ and /eː/ appear in to be phonemic in most varieties of Arabic, they can be used in Modern Standard Arabic in some stable loanwords or foreign names, e.g. كوكاكولا /kokaˈkoːla/, شوكولاتة /ʃokoˈlaːta/, دكتور /dukˈtoːr/ or /dokˈtoːr/, جون /ʒoːn/, توم /tom/, بلجيكا /belˈʒiːka/, سكرتير /sekreˈteːr/ or /sekerˈteːr/, etc. Foreign words have a liberal sprinkling of long vowels, as their word shapes do not conform to standardized prescriptive pronunciations written by letters for short vowels; when in need the letters ي or و are always used to render the long vowels /eː/ and /oː/.
In the most formal of conventions, pronunciation depends upon a speaker's background. The number and phonetic character of most of the 28 consonants has a broad degree of regularity among Arabic-speaking regions. Note that Arabic is rich in uvular and pharyngealized sounds; the emphatic coronals cause assimilation of emphasis to adjacent non-emphatic coronal consonants. The phonemes /p/ ⟨پ⟩ and /v/ ⟨ڤ⟩ are not considered to be part of the phonemic inventory, as they exist only in foreign words and they can be pronounced as /b/ ⟨ب⟩ and /f/ ⟨ف⟩ depending on the speaker.. The standard pronunciation of ⟨ج⟩ /d͡ʒ/ varies regionally, most prominently in the Arabian Peninsula, parts of the Levant, northern Algeria and Sudan, it is considered as the predominant pronunciation of Literary Arabic outside the Arab world, in most of Northwest Africa and the Levant, in most of Egypt and a number of Yemeni and Omani dialects. Long consonants are pronounced like short consonants, but last longer. In Arabic, they are called mushaddadah, but they are not pronounced any "stronger".
Between a long consonant and a pause, an epenthetic occurs, but this is only common across regions in West Asia. Arabic syllable structure can be summarized as follows, in which parentheses enclose optional components
Urmia is the largest city in West Azerbaijan Province of Iran and the capital of Urmia County. It is situated at an altitude of 1,330 metres above sea level, is located along the Shahar Chay river on the Urmia Plain. Lake Urmia, one of the world's largest salt lakes, lies to the east of the city, the mountainous Turkish border area lies to the west. Urmia is the 10th most populated city in Iran. At the 2012 census, its population was 667,499, with 197,749 households; the city's inhabitants are predominantly Azerbaijanis. There are minorities of Kurds and Armenians; the city is the trading center for a fertile agricultural region. The Christian history of Urmia is well preserved, is evident in the city's many churches and cathedrals. An important town by the 9th century, the city has had a diverse population which has at times included Muslims, Jews, Bahá'ís and Sufis. Around 1900, Christians made up more than 40% of the city's population. Richard Nelson Frye suggested Urartian origin for the name while T.
Burrow connected the origin of the name Urmia to Indo-Iranian urmi- "wave" and urmya- "undulating, wavy", which comes from the local Assyrian folk etymology for the name which related mia to a Syriac word meaning "water". Hence Urmia means "Watertown" – a name befitting a city situated by a lake and surrounded by rivers, a kind of "cradle of water"; as of 1921, Urmia was called and Urmi. During the Pahlavi Dynasty, the city was called Rezaiyeh after Rezā Shāh, the dynasty's founder, whose name derives from the Islamic concept of rida via the Eighth Imam in Twelver Shia Islam, Ali al-Ridha. According to Vladimir Minorsky, there were villages in the Urmia Plain as early as 2000 BC, with their civilization under the influence of the Kingdom of Van. Excavations of the ancient ruins near Urmia led to the discovery of utensils that date to the 20th century BC. In ancient times, the west bank of Urmia Lake was called Gilzan, in the 9th century BC an independent government ruled there, which joined the Urartu or Mana empire.
Nestorians who did survive the invasion of Baghdad by Timur fled through northern Iraq up into the Hakkari Mountains to the west of Lake Urmiya and the area remained as their homeland untill 19th century. During the Safavid era, the neighboring Ottoman Turks, who were the archrivals of the Safavids, made several incursions into the city and captured it on more than one occasion, but the Safavids regained control over the area; when in 1622, during the reign of Safavid king Abbas I Qasem Sultan Afshar was appointed governor of Mosul, he was forced to leave his office shortly afterwards due to the outbreak of a plague. He moved to the western part of Azerbaijan, became the founder of the Afshar community of Urmia; the city was the capital of the Urmia Khanate from 1747–1865. The first monarch of Iran's Qajar dynasty, Agha Muhammad Khan, was crowned in Urmia in 1795. Due to the presence of a substantial Christian minority at the end of the 19th century, Urmia was chosen as the site of the first American Christian mission in Iran in 1835.
Another mission was soon underway in nearby Tabriz as well. During World War I the population was estimated by Dr. Caujole to be 30,000, a quarter of which were Assyrians and 1,000 Jews. During the 19th century, the region became the center of a short-lived Assyrian renaissance with many books and newspapers being published in Syriac. Urmia was the seat of a Chaldean diocese. At the beginning of the First World War tens of thousands of Assyrians and Armenians from the Ottoman Empire found refuge in Urmia. During the war, the city changed hands several times between the Russians and the Ottoman troops and their Kurdish allies in the following two years; the influx of Christian refugees and their alliance with the Russians angered the Muslims who attacked the Christian quarter in February 1918. The better armed Assyrians managed to capture the whole city following a brief battle; the region descended into chaos again after the assassination of the Assyrian patriarch Shimun XIX Benyamin at the hands of Simko Shikak one month later.
Turkish troops and Simko managed to take and plunder the city in June/July 1918. Thousands of Assyrians were massacred as part of the Assyrian Genocide. According to the 2016 census, population of Urmia city is 736,224, with an annual growth rate of 2.0% and an average of 3.27 people per household. The city has been home to various ethnic groups during its history; the population of Urmia in the early Islamic period was Christian. At the beginning of the 20th century, the city had a significant Christian minority with the Christian population of the town consisting of 40–50 % of the total population. According to Macuch, Ishaya, the city was the spiritual capital of the Assyrians, who were influenced by four Christian missions, established in the city in the period from 1830 to the end of World War I. A large number of the Assyrians and Armenians were killed in 1914 during the Armenian and Assyrian genocides, which resulted in a change in the city's demographics. During the era of Reza
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