Glottis

Anatomia (Article)
This interactive resource provides animated views of the internal structures of the larynx and the mucosa, allowing the user to view animations of muscle contraction in all planes, complete with descriptions and definitions. Additionally, images of a larynx dissection, video clips of normal vocal fold function and of vocal fold pathologies, and some clinical case studies are available. Learning objectives and self-quizzes are also included. (posted 5:28 PM, February 8, 2015)

Interactive Atlas of the Larynx (Article)
An interactive diagram of the larynx. This resource demonstrates how the larynx is constructed and how different parts of the larynx work separately and together. Includes visuals of how the intrinsic muscles of the larynx work. A wonderful resource for any undergraduate pedagogy class. (posted 8:31 PM, November 13, 2014)

How the LCA and IA muscles adduct (close) the glottis (Article)
This very brief (1 minute) video shows a demonstration of the action of the lateral cricoarytenoids and interaryenoids in adducting the vocal folds and closing the posterior glottic gap, using an excised cow larynx. THere is a biref demonstration of both the posterior cricoarytenoid and the cricothyroid muscles. (posted 2:34 PM, August 27, 2014)

Muscles of the Larynx-Part 1 (Article)
This 8-minute video uses 3-D computer graphics to give a clear basic introduction to the muscles attached to the cricoid cartilage. (posted 2:34 PM, August 27, 2014)

Breathy/Paralysis voice sample (Article)
This short audio clip is of a middle-aged woman with a vocal fold paralysis. The definition of breathiness is turbulence noise of air escaping through the incompletely closed glottis. This is clearly heard in this sample. You can also hear that she runs out of breath quickly. (posted 2:34 PM, August 27, 2014)

breathy/vascular lesion voice sample (Article)
This short audio clip is of a high school aged female singer with a vascular (blood filled) lesion of the right vocal fold. The vocal fold is also irregular, swollen and stiff, and therefore does not vibrate well. Because of the irregularity of the vibratory margin of the vocal fold, the glottis does not close completely. The definition of breathiness is turbulence noise of air escaping through the incompletely closed glottis. This can be heard in this sample. You can also hear that she runs out of breath quickly. However, the breathiness is not as severe or apparent as it is in the breathy/paralysis clip. One could think that she is simply using a breathy style in the context of the song, or that she is young and needs to "focus" or "support" the tone. In fact, however, the vocal fold is badly damaged. (posted 2:34 PM, August 27, 2014)

subharmonic/pressed voice voice sample (Article)
This short audio clip is of an adult male professional singer with a complaint of noise in his voice. The listener can hear the mild roughness in the quality. In this case, the laryngeal exam showed there was no lesion, but the vocal folds were "pressed" during phonation; that is, the closed phase of the vibratory cycle was long, and impact of the vocal folds was high. Also, the ventricular folds squeezed together somewhat when the tone became more rough. The resulting quality is known as strain. The "buzzy" quality is the result of a subharmonic, an irregular vibration at a frequency that is lower than the fundamental frequency of vibration. (Remember that the fundamental frequency provides the pitch.) The subharmonic is generated because of the irregular and asymmetrical pressure at the glottis. (posted 2:34 PM, August 27, 2014)

left paresis pre-surgery singing video (Article)
This video is one of four in a series showing the larynx of an adult female with a left vocal fold paresis (incomplete paralysis). Note that the left vocal fold does move slightly, but is very limited compared to the right. The paresis results in weak glottic closure, which prevents normal vocal fold vibration. This video shows the larynx prior to a thyroplasty, that is, surgical placement of an implant that provides improved glottic closure and therefore better vibration. This series of videos provides a good demonstration of the concept of entrainment, in which the vocal folds become "entrained" in the airstream to vibrate, as long as they are close enough together, and have similar underlying muscle tone. (posted 2:34 PM, August 27, 2014)

left paresis pre-surgery stroboscopy video (Article)
This video is one of four in a series showing the larynx of an adult female with a left vocal fold paresis (incomplete paralysis). Note that the left vocal fold does move slightly, but is very limited compared to the right. The paresis results in weak glottic closure, which prevents normal vocal fold vibration. This video shows the larynx prior to a thyroplasty, that is, surgical placement of an implant that provides improved glottic closure and therefore better vibration. This series of videos provides a good demonstration of the concept of entrainment, in which the vocal folds become "entrained" in the airstream to vibrate, as long as they are close enough together, and have similar underlying muscle tone. The stroboscopy makes it clear that entrainment is often not achieved, leaving the vocal folds to vibrate separately, often at different frequencies. When the pitch is high enough, and there is enough longitudinal tension along the left vocal fold, the right vocal fold can vibrate against it with adequate regularity to a achieve a stable frequency, although the glottic closure is insufficient for much volume. (posted 2:34 PM, August 27, 2014)

left paresis post-surgery singing video (Article)
This video is one of four in a series showing the larynx of an adult female with a left vocal fold paresis (incomplete paralysis). Note that the left vocal fold does move slightly, but is very limited compared to the right. The paresis results in weak glottic closure, which prevents normal vocal fold vibration. This video shows the larynx after thyroplasty, that is, surgical placement of an implant that provides improved glottic closure and therefore better vibration. The improvement with better glottic closure is quite dramatic. This series of videos provides a good demonstration of the concept of entrainment, in which the vocal folds become "entrained" in the airstream to vibrate, as long as they are close enough together, and have similar underlying muscle tone. (posted 2:34 PM, August 27, 2014)

left paresis post-surgery stroboscopy video (Article)
This video is one of four in a series showing the larynx of an adult female with a left vocal fold paresis (incomplete paralysis). Note that the left vocal fold does move slightly, but is very limited compared to the right. The paresis results in weak glottic closure, which prevents normal vocal fold vibration. This video shows the larynx after thyroplasty, that is, surgical placement of an implant that provides improved glottic closure and therefore better vibration. This series of videos provides a good demonstration of the concept of entrainment, in which the vocal folds become "entrained" in the airstream to vibrate, as long as they are close enough together, and have similar underlying muscle tone. The improvement in entrainment provided by the improved glottic closure allows for much more normal vibration of the vocal folds. (posted 2:34 PM, August 27, 2014)

polyp video (Article)
This video shows a larynx with a hemorrhagic (blood filled, aka vascular) polyp on the right vocal fold. The polyp results in incomplete closure of the glottis, and irregular vibration of the vocal folds. The varies according to pitch and loudness. The video makes it clear why the singing voice quality in the audio clip varies from markedly rough to normal. (posted 2:34 PM, August 27, 2014)

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