The Normal Voice

Velopharyngeal Closure

To provide orientation, the endoscope is threaded through the nose and focused on the back of the nose before it joins the mouth. In the video straight ahead is where the adenoids would be (small in this person). The floor is the soft palate (back aspect of the roof of mouth) and uvula (the little hanging thing in the back of the mouth).

To prevent a nasal sounding speech (as well as to prevent food/liquids from coming out the nose when swallowing), the soft palate rises and makes a tight seal with the posterior aspect of the nasopharynx (back of the throat). In the video, one can see the rise and fall of the soft palate. Abnormal closure can be found under the "Nasal Sounding Speech".

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Vocal Cord on Phonation (Glide)

When the vocal cords come together and start vibrating, it creates what we perceive as the voice. When the vocal cord is short and fat, the pitch is low. As the vocal cords become tighter and thinner by lengthening, the pitch becomes higher (just like a violin where the thinner and tighter string is higher than the thicker and more relaxed string). Here is a video sequence depicting a low /e/ glide up to a high /e/. Note the thickness and length of the vocal cord with the rise in pitch.

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Pharyngeal Muscle Use on Phonation (Glide)

Although vocal cords play an important role in phonation, the musculature around the throat modifies the resonance/harmonics of a given pitch so what comes out the mouth sounds pretty. Generally speaking, the higher the pitch, the smaller the diameter of the throat above the vocal cords. The lower the pitch, the bigger the diameter of the throat. This is analogous to organ pipes in which the large diameter organ pipes produce a lower pitch than the smaller diameter organ pipes. Observe the throat diameter as the pitch increases and decreases in this slow glide up and down. More subtle, note how the voicebox rises (camera is still) with increasing pitch, just like a higher pitch organ pipe is shorter than a lower pitch organ pipe.

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Differences Among Endoscopes

There are different ways to visualize the vocal cords in action. Click on one of the exam types to view the video. Keep in mind that all these exams were performed on the same person. To see how endoscopy is performed, click here.

• 70° Rigid Endoscope (Top Video)
• Flexible Fiberoptic Endoscope (Middle Video)
• Chip-On-Tip Flexible Endoscope (Bottom Video)

Rigid endoscopy is performed via the mouth and provides excellent light and image quality. However, the subject really can't talk other than to phonate a basic /e/ and the gag reflex could be significant.

Flexible fiberoptic endoscopy is performed through the nose and provides greater phonation ability for the patient with minimal if any gag reflex, but the image quality is poor with a significant moire effect. Why even use this endoscope? It has the smallest diameter and is the most comfortable for the subject. In our practice, this scope is mainly used on pediatric patients (infants to tween years).

Chip-On-Tip flexible endoscopy is a fully digitized system, also performed via the nose, which has all the advantages of a regular flexible fiberoptic endoscope, but with superior images. The one downside is that the diameter of the scope is bigger and not usually tolerated by pediatric patients. Most of the exams provided on this website were obtained using this digital system except for most footage shown under "nasal speech" section (most are kids).

Believe it or not, there is a digital system one step higher than what is shown here and that is a high speed video system (our office does not utilize one). Although digital videos are great, the capture rate on a standard system such as the one we use occurs at 25-30 frames/sec. A high speed video (HSV) system captures images at 2000 frames/sec! The one downside with HSV systems is that the exam is performed through the mouth with a rigid scope which often gags patients.

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