Glottis

4 Key excerpts on "Glottis"

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  eBook - ePub

  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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  eBook - ePub

  Learning about Linguistics

  • F.C. Stork, J.D.A. Widdowson(Authors)
  • 2014(Publication Date)
  • Routledge

    (Publisher)

  The LUNGS have the task of oxygenating the blood and the mechanism of breathing allows us to take air into the lungs so that oxygen can be extracted from it. In this way we can see that even the process of moving the air into and out of the vocal tract has a more important primary purpose other than speech. The TRACHEA, or windpipe, leads from the lungs up towards the larynx. The LARYNX is a complex mechanism of bone, cartilage and tissue which enables us to seal off the lungs from the outside world: a function which is essential if, for example, we want to bend down to pick up a heavy weight. In Fig. 1 the larynx is shown schematically to represent the VOCAL CORDS which are part of the internal structure of the larynx. The space between the vocal cords is called the Glottis, and the fine muscular control which we can exercise over the vocal cords, and hence the Glottis, is extremely important not only for speech but for the whole mechanism of breathing. Fig. 1 If the Glottis is fully open air is allowed to pass through the larynx with little resistance, and this is the position of the vocal cords for normal breathing which is usually more or less silent. As we have already mentioned we can seal off the air in the trachea and lungs by means of the larynx, and this is done by bringing the vocal cords together making a complete and airtight closure of the Glottis. This mechanism allows us to retain pressure below the Glottis in the lungs and trachea. The technical term for this is SUBGLOTTAL PRESSURE. Control of subglottal pressure is essential for speech. The Glottis can also be closed by the action of the vocal cords in such a way that the closure is not airtight but so that the air has to push its way through with a certain amount of effort. When the molecules of air push the vocal cords out of the way, the elasticity in the muscle causes the vocal cords to oscillate back to their original position. This movement is very rapid and constitutes a vibration

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  eBook - ePub

  Auditory Perception

  A New Synthesis

  • Richard M. Warren, Arnold P. Goldstein, Leonard Krasner(Authors)
  • 2013(Publication Date)
  • Pergamon

    (Publisher)

  Fig. 7.1 ). The subglottal system delivers air under pressure to the larynx (located behind the Adam’s apple) which contains a pair of vocal folds (also called vocal cords). The opening between the vocal folds is called the Glottis, and the rapid opening and closing of the glottal slit interrupts the air flow, resulting in a buzz-like sound. The buzz is then spectrally shaped to form speech sounds or phonemes by the supralaryngeal vocal tract having the larynx at one end and the lips and the nostrils at the other. In addition to modifying the laryngeal buzz, the vocal tract also is used to produce noises and plosive sounds with phonetic significance.

  Fig. 7.1 Anatomical structures involved in speech production. The subglottal system delivers air under pressure to the larynx. The vocal folds in the larynx are capable of generating broad-band sounds. The supraglottal system can spectrally shape the sound produced in the larynx by altering dimensions along the vocal tract, and by opening or closing access to the nasal passages. The supraglottal system is also capable of adding some hisses and pops of its own.

  The Subglottal System

  The Glottis remains open during normal breathing without phonation. Inhalation is accomplished through expansion of the chest cavity, largely through contraction of the diaphragm and the external intercostal muscles. Exhalation is accomplished mainly through elastic recoil when the contraction of the muscles used for inhalation ceases. However, during more active breathing, including that accompanying speaking, the passive compression of air in the lungs following active inhalation is supplemented by contraction of the internal intercostal and abdominal muscles. The air passes from the lungs through the windpipe or trachea up to the larynx. During speaking, the subglottal pressure is usually equivalent to about 5 to 10 cm of water (that is, equal to the force per unit area exerted by a water column of this height), although during very loud shouting it can rise to the equivalent of 60 cm of water. The average flow rates during speech are roughly 150 to 200 cm3 /sec, and the average inhalation for speech about 500 to 800 cm3

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  eBook - ePub

  An Introduction to the Science of Phonetics

  • Nigel Hewlett, Janet Mackenzie Beck(Authors)
  • 2013(Publication Date)
  • Routledge

    (Publisher)

  In some other languages of the world there are, in fact, a few speech sounds that can be produced while holding the breath. This is because airflow within the vocal tract can be initiated by movements of the larynx or the tongue rather than by respiratory effort. Such sounds are relatively rare, however, and are considered in more detail in chapter 6. For the rest of this chapter, it may be assumed that all sounds are produced using a pulmonic egressive airstream. Practice 4.1 Take a breath and count slowly and clearly until you run out of breath. Notice what happens as you begin to run short of air. You will probably become increasingly aware of the way in which pulses of air are actively pushed out of the lungs using a combination of downward and inward movement of the ribs. Note how far you are able to count before you are forced to stop by lack of air. Try the same counting task while breathing in. Note any changes in the quality of your voice. Are you able to count as far on one breath? Phonation A major classificatory distinction in phonetics relates to what is happening as the air stream passes through the larynx. A fuller discussion of this process is given in chapter 18, but the brief description that follows should allow an adequate level of understanding for the early stages of phonetic analysis. The larynx is situated within the neck, just above the top of the trachea. It is a surprisingly complex structure of muscle and other soft tissues within a protective framework of cartilages, and it probably evolved primarily as a mechanism for protecting the airway. The larynx is usually easily located by identifying the thyroid cartilage. This is the largest cartilage of the larynx and forms a protective and supporting girdle around the front of the airway. It can be felt, and often seen, as a protuberance at the midline of the neck. It tends to be more prominent in men than in women, and is hence often known as the Adam’s apple

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