Glottis

8 Key excerpts on "Glottis"

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  Understanding Phonetics

  • Patricia Ashby(Author)
  • 2013(Publication Date)
  • Routledge

    (Publisher)

  front aretynoid cartilages and vocal folds tightly closed thyroid cartilage back The role of the larynx 28 which becomes trapped below in the sub-glottal space (in the trachea, in fact). When this happens, we articulate the sound known as the glottal stop. This is widely used and will be found in languages across the world. It is very characteristic of all London Englishes (Cockney, MLE, Estuary) and is often represented in literature by authors attempting to create an impression of such accents by replacing certain t’s with an apostrophe as in wha’ a lo’ of ho’ wa’er (what a lot of hot water). The process involved here has an extremely graphic name: t-glottalling (see page 43 for more about this.) Like the h-sounds, the glottal stop also has its own symbol, [ʔ]. (Don’t confuse this with a question mark – there is no dot at the bottom.) 2.4 THE LARYNX AS A PITCH MODULATOR We have already talked about pitch and its relationship to the rate of vibration of the vocal folds. Languages exploit this in two principal ways. Some languages use it to make distinctions between different words. This is a lexical use of pitch and such languages are called tone languages. Tone languages are found all over the world, but they are particularly prevalent in East and South- East Asia where you find all the different Chinese languages (Modern Standard Chinese, Cantonese, Hokkien, etc.), Thai, Burmese and so forth. Tone languages are also found in Africa (Hausa, Zulu, etc.) and in the Americas where some of the indigenous American Indian languages are tone languages (Navajo, Chatino, etc.). How lexical tone works can be illustrated by this example from Thai. For a single syllable [k h a] (which sounds a little bit like the English word car spoken with an Australian accent), the pitch on which the syllable is spoken changes and for each different pitch pattern, there is a different meaning.

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  A Critical Introduction to Phonetics

  • Ken Lodge(Author)
  • 2009(Publication Date)
  • Continuum

    (Publisher)

  I shall deal first with the egressive pulmonic airstream and the modulating mechanisms, and then consider the more restricted types of airstream at the end of the chapter. 2.2 The vocal cords and the Glottis Within the larynx are the vocal cords (also called vocal folds), two muscular flaps which can be moved into various positions to interfere with the airflow. The part of the windpipe that goes through the larynx is called the Glottis. We need to consider the ways in which the vocal cords operate in more detail in relation to egressive pulmonic air. The larynx is a casing made of cartilage and muscle around the windpipe (trachea), containing the vocal cords stretched across the Glottis. At the front of the larynx the thyroid cartilage is seen from the outside of the throat as the 'Adams apple' in men and 'Eves wedding ring' in women; the protusion of the thyroid cartilage is usually greater in men than in women. The vocal cords can be moved into different positions by the operation of the arytnoid cartilages to which they are attached. The arytenoid cartilages are generally thicker in men than in women, and the cords themselves are generally longer in men than in women. (Note that since the vocal cords are primarily intended to stop for-eign substances entering the lungs, tar from smoking cigarettes becomes lodged on them; this means that heavy smokers often develop deep voices because they cannot vibrate their cords quickly enough to produce the usual higher pitch ranges.) 16 A Critical Introduction to Phonetics Figure 2.2 The larynx. There are basically five different ways in which the vocal cords can be placed in relation to one another across the Glottis. The resultant effects these differ-ent positions of the cords have on speech are referred to as phonation. 2.2.1 Closed Glottis As we saw in section 2.1, the vocal cords can be shut tight together, completely obstructing the flow of air through the Glottis.

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  Phonetics

  Transcription, Production, Acoustics, and Perception

  • Henning Reetz, Allard Jongman(Authors)
  • 2011(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  The space between the vocal folds, reaching from the bottom side of the vocal folds to their top, is called the Glottis. People often speak about the Glottis as if it were an organ, as in, for example: “opening the Glottis”; it is not. The Glottis is essentially the whole area of the vocal folds that is involved in sound production. It should be pointed out that even with maximal glottal opening, the vocal folds still block about 50 percent of the diameter of the trachea, which makes humans not very efficient in terms of the respiratory process.

  To summarize, the larynx is located on top of the trachea. It is partly suspended by ligatures and muscles from the hyoid, which is itself attached by ligatures and muscles to the tongue root. The thyroid, which forms the main body of the larynx, is located above the cricoid. The thyroid and the cricoid can rotate relative to each other. The vocal folds can be tensed and released by the rotating movement of the thyroid and the cricoid. The positioning of the vocal folds can be changed by the arytenoids. The arytenoids, which are located on top of the cricoid, can be tilted. Tilting the arytenoids downwards and inwards adducts the vocal folds, causing them to close. Tilting the arytenoids upwards and outwards abducts the vocal folds, causing them to open. Tensing and releasing the vocal folds influences their rate of vibration (see Section 5.2.2), which is the result of an interaction between the pulmonic airstream and the Glottis. The Glottis can be open (for example, during breathing or the production of voiceless sounds), it can be closed (for example, during swallowing or the production of ejectives; see Section 6.1.1), or it can be partially open with the vocal folds abducted halfway to a point where they start vibrating in the pulmonic airstream. This vibration (or oscillation) is described in detail in the next section.

  5.2.2 Vocal fold vibration

  The vibration of the vocal folds is a very complex movement. Generally speaking, the vocal folds open up from bottom to top and from back to front. The closing of the vocal folds also proceeds from bottom to top, but along the horizontal axis it starts from the middle, closing forwards and backwards at the same time. The closure of the vocal folds is often incomplete, especially for women, since a small triangle next to the arytenoids, at the posterior (back) end of the vocal folds, remains open.

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  Introducing Linguistics

  Theoretical and Applied Approaches

  • Joyce Bruhn de Garavito, John W. Schwieter(Authors)
  • 2021(Publication Date)
  • Cambridge University Press

    (Publisher)

  The intercostals raise the ribcage to allow air to flow into the lungs during inhalation, while the diaphragm helps to control the release of air so that we can speak for a reasonable period of time between breaths. The next section of the speech production system begins above the larynx (see Figure 2.2) and is where most of the individual sounds of language are formed. This section is called the supralaryngeal, or supraglottal (i.e., above the Glottis) articulatory system. This diagram is commonly called a midsagittal diagram. It is called as such because it represents a cross-sectional view of the vocal tract, divided from the tip of the nose to the back of the head. Nasal Cavity Oral Cavity Tongue EpiGlottis Teeth Lips Lips Alveolar Ridge Hard Palate Velum (soft palate} Uvula Pharynx Larynx Glottis Vocal folds Figure 2.2 Midsagittal diagram of the supraglottal articulatory system 29 2.2 Speech Production 2.2.3 The Larynx When air is expelled from the lungs, it passes through the trachea (windpipe) and then through the larynx. The larynx is a box-like structure made of cartilage and mus- cle, commonly known as the voicebox or Adam’s apple. The larynx consists of the thyroid cartilage, which sits on the ring-shaped cricoid cartilage. The vocal folds (or cords) are along the side of the thyroid cartilage and are opened or closed by the muscles attached to the arytenoid cartilages. Figure 2.3 shows the larynx from the front. As air is pushed through the space between the vocal folds, or the Glottis, different types of voicing occur, depending upon the position of the vocal folds. When the vocal folds are held tightly together, they vibrate very rapidly when air passes between them as seen in Figure 2.4(a). This produces voiced sounds. Voicing is a low buzzing or vibrat- ing sound that accompanies vowels and some consonants.

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  From Speech Physiology to Linguistic Phonetics

  • Alain Marchal(Author)
  • 2010(Publication Date)
  • Wiley-ISTE

    (Publisher)

  This measure shows deviations from a norm and is often used to describe various voice pathologies, such as noisy or raucous voice; – “shimmer” measures the variability of amplitude over cycles and gives an indication of glottal flow. 2.8. The linguistic functions of laryngeal activity The larynx is the first place where the airflow from the lungs can undergo important modifications. Airflow passage can be relatively free, completely blocked or restricted in varying degrees (see Figure 2.18). We have seen how fine and how complex laryngeal adjustment can be. Every language makes great use of the contrasts deriving from modifications to airflow in the larynx. Catford (1977) describes 10 glottal states that can be linguistically significant. For Ladefoged (1971), seven states of the vocal folds and larynx are enough to account for the linguistic contrasts found in the languages of the world. 2.8.1. Glottal states and phonation types Following Ladefoged (1971), we identify seven phonation types: – modal voice; – voicelessness; 60 From Speech Physiology to Linguistic Phonetics – breathy voice; – murmur; – laryngealization; – glottal occlusion; – whisper. 2.8.1.1. Modal voice The vocal folds close along their whole length. Adductive tension and medial compression are moderate. An increase in the airflow rate of air coming from the lungs produces suction (the Bernoulli phenomenon) which completes the closure of the vocal folds. There follows an increase in subglottal pressure: when this becomes greater than the forces of adduction, it forces its way through, pushing the vocal folds to the sides. The opening and closing cycle of the Glottis is thus repeated in a semi-periodic fashion, as long as tension, airflow and air pressure are sufficient to maintain the vibration of the vocal folds. In modal voice, the necessary minimum subglottal pressure is 2-3 cm H 2 O. In normal speech, it is 10-15 cm H 2 O. The transglottal passage of air varies between 50 and 350 cc/s.

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  The Sounds of Language

  An Introduction to Phonetics and Phonology

  • Elizabeth C. Zsiga(Author)
  • 2012(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  The closure is aided by the epiGlottis, a flap of tissue attached to the base of the tongue, which folds down over the top of the larynx, which rises to meet it, during swallowing. Try swal- lowing a few times, paying attention to the muscular sensations. Can you feel the larynx rising up, and the tension in the throat that corresponds to the lowering of the epiGlottis? 1.1 In Focus Human infants, who have very poor muscle control and spend a lot of time drinking while lying down, are born with the larynx high in the throat, similar to the arrangement typical of other primates. Thus, the liquid the baby ingests passes around the sides of the trachea rather than over the top, preventing choking. The larynx lowers to the normal human position over the first months of life, as the child gains control over the muscles of the neck and head, learns to sit up, and begins to eat solid food and to babble. The tradeoff for the lowered larynx position in the human is significant, however. With the trachea down and out of the way, humans have an open space, the pharynx, at the back of the mouth behind the tongue. This open space allows greater freedom for movement of the tongue, making a wide range of vowel and consonant sounds, and thus human language, possible. 1.2.3 the supra-laryngeal vocal tract Thus far, we’ve seen that the lungs provide the moving air on which speech is based, and the larynx adds (or not) the vibration of voicing and control of pitch. It is the structures above the larynx that move to further shape and constrict the air as it moves out from the lungs, creating distinctions between individual speech sounds. It is useful to divide the structures of the mouth into the active articulators and passive articulators. The active articulators move toward the passive articulators in order to constrict and shape the airstream. The labels for the active and passive articulators are shown in Figure 1.8.

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  Phonetics

  Transcription, Production, Acoustics, and Perception

  • Henning Reetz, Allard Jongman(Authors)
  • 2020(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  During speech, air flows out of the lungs through the trachea and the larynx and into the vocal tract. This process is actively supported and controlled by the exhalation mus-cle group. Precise control of the air pressure in the trachea is required because the intensity of the speech signal depends partly on this parameter. As already mentioned, the role of the larynx is essential for speech production, and is treated in detail in the next section. 5.2 Structure and function of the larynx The larynx, which is located inside the neck on top of the trachea, contains the vocal folds. Speech sounds are called voiced when the vocal folds vibrate during their production. Speech sounds are called unvoiced or voiceless when the vocal folds do not vibrate (see Section 2.1, but see Section 6.3 for an alternative defini-tion of voicing for plosives in several languages). The vibration of the vocal folds attributes a quality to the speech which is perceived as pitch , giving a certain “melody” to a word or sentence. The next sections cover the anatomy of the larynx and the principles of vocal fold vibration. Physiology of the Vocal Apparatus 75 5.2.1 Anatomy of the larynx The larynx is an adjustable cartilage tube through which air flows with each breath. It is located on top of the trachea and is suspended from the hyoid bone , a horseshoe‐shaped ring located in the upper part of the neck, which supports the tongue root (see Figure 5.5a and b). The trachea consists of cartilage rings with an opening at the back, making them look like small horseshoes. The back part of the half‐rings directly touches the esophagus (gullet) and is made airtight by its tissues and the trachealis muscle . Between the cartilage rings, a series of ligaments surround the entire trachea, enclosing it airtight. Like the trachea, the larynx on top of it consists of cartilage, muscles, and liga-ments.

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  Ear, Nose and Throat Diseases

  With Head and Neck Surgery

  • Hans Behrbohm, Oliver Kaschke, Tadeus Nawka, Andrew C. Swift(Authors)
  • 2009(Publication Date)
  • Thieme

    (Publisher)

  Sound produced in the Glottis travels through the air-filled supraglottic space, the throat, and the oral and nasal cavities before being emitted into the environment ( Fig. 5.2 ). The air in this vocal tract resonator has multiple resonance frequencies at which it enhan-ces existing spectral components ( harmonics ). These vocal tract resonances ( formants ) act as filters that shape the spectrum of the sound generated by Voice 331 1 2 3 4 5 6 7 8 Fig. 5.1 Characteristic fea-tures of normal vocal fold vibra-tion as seen in stroboscopy. 1 , The lower part of the Glottis starts to open; 2 , the upper part of the Glottis starts to open; 3 , the lower and upper part of the Glottis open; 4 , the lower part of two Glottis is maximally open, and the upper part of Glottis is still opening; 5 , the lower part of the Glottis closes and is visible; 6 , the lower and upper part of the Glottis close, and a mucosal wave propagates on the surface; 7 , the lower part of the Glottis is closed; 8 , the upper part of the Glottis is closed. Table 5.1 Layers of the vocal folds: anatomical tissue layers compared with functional layers in the body-cover model Five tissue layers Body-cover model Epithelium Mucosa Cover Lamina propria Superficial layer Intermediate layer Vocal liga-ment Transi-tion Deep layer Thyroarytenoid muscle (vocalis) Muscle Body the source (larynx) to produce an output signal that is a combination of source and filter ( Fig. 5.3 ). The different sounds of human speech ( phonemes ) de-pend strongly on formants. In all human languages, vowels are distinguished by the frequencies of the two lowest formants ( Fig. 5.4 ). The third, fourth, and fifth formants are of greater significance to personal voice timbre. ■ Voice Diagnosis The following aspects need to be taken into account when assessing common forms of dysphonia.

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