Vocal fold vibration

The Voice is Like a Car" (how does the voice work) (Article)
Dr. Titze and other experts explain vocal production by means of analogies to how a car works. This is highly simplified, but graphics are helpful. A highlight is a famous movie scene, in which the voice signal sounds as it would without the filtering of the vocal tract. (posted 2:34 PM, August 27, 2014)

normal larynx video without and with stroboscopy (Article)
This video shows the larynx of a college-age singer with a healthy larynx. The vibration is seen as a blur at first, but halfway through, the halogen light is turned off and the strobe (xenon) light is turned on. The stroboscopy gives the optimal illusion of slow-motion vibration, allowing us to see the mucosal wave. Notice the symmetry and regularity of the normal mucosal wave. (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)

More About Resonant Voice: Chasing the Formants But Staying Behind Them (Article)
To achieve a more resonant voice, a formant is not placed directly on a harmonic, but rather slightly above a harmonic. Stated conversely, the harmonic chases the formant, but never quite catches up with it. The advantage of this maneuver is a strengthening of all harmonics, not just a single one. (posted 2:34 PM, August 27, 2014)

What Makes a Voice Acoustically Strong? (Article)
A voice is acoustically strong if the glottal flow can be reduced from a high value to a low value in a short time interval. The total collapse of flow per second is called the maximum flow declination rate. It can be increased by increasing lung pressure, by increasing vibration at the bottom of the vocal fold, or by narrowing the acoustic tube immediately above the vocal folds. In practice, a combination of these control strategies is probably utilized by singers. (posted 2:34 PM, August 27, 2014)

Vowel Modification Revisited (Article)
Modification involves shading vowels with respect to the location of vowel formants, so the sung pitch or one of its harmonics receives an acoustical boost by being near a formant. The goals of modification include a unified quality, throughout the entire range, smoother transitions between register, enhanced dynamic range and control, and improved intelligibility. (posted 2:34 PM, August 27, 2014)

The F0-F1 Crossover Exercise (Article)
The author has a long-term goal to understand and appreciate proven exercises and vocalizes used by singing teachers. One such exercise is the downward glide in pitch on a vowel [u] or [o], beginning on about D5 and ending one to two octaves lower. (posted 2:34 PM, August 27, 2014)

How Are Harmonics Produced at the Voice Source? (Article)
In summary, harmonics in the glottal waveform are produced by adducing the vocal folds sufficiently so that they can collide. This changes the waveform from a simple oscillatory shape that has only one frequency. Alternately, or in conjunction with collision, the vocal tract can be engaged to feed back an acoustic wave to the glottal flow. (posted 2:34 PM, August 27, 2014)

How to Find a Voice Doctor (Article)
The purpose of the article is to help the individual, teacher, and family member navigate through the vocal health care system. The different types of voice care professionals involved in voice evaluation and treatment are mentioned. A variety of key components of voice evaluation are described as well as assists in providing the reader with a method to find a voice care physician. (posted 2:34 PM, August 27, 2014)

Dispelling Vocal Myths. Part 3: "Sing OVER Your Cold! (Article)
Continuing the series begun in 2010, Michael aims to clarify misconceptions about vocal production. In this installment Michael and Goding examine some myths and truths about vocal fold swelling, particularly as it pertains to upper respiratory infection (URI). For part one see 66, no. 5 (547-551); part two 67, no. 4 (417-421); part four 69, no. 2 (167-172). (posted 2:34 PM, August 27, 2014)

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