Segmental Vibration
In the normal larynx, segmental vibration occurs when both chest and falsetto (head) registers are produced by vibration of the anterior 2/3 of the vocal cords. The posterior 1/3 is “inhabited” by the arytenoid cartilage and does not vibrate.
In certain pathological circumstances such as displayed in the photo sequences below, only a small part of the vocal cords vibrates.
This segmental vibratory phenomenon is typically seen in vocal cords that are damaged—such as by vocal nodules, polyps, cyst, scarring, etc. In such persons, upper voice is typically particularly impaired, until, as the person continues to try to ascend the scale, suddenly a crystal-clear “tin whistle” kind of voice emerges and may continue upwards to very high pitches.
Some in the past have talked about flagelot, flute, bell, or whistle register. We suspect that this was in the days before videostroboscopy and at least in some cases may have been segmental vibration.
The best way to determine if what sounds like a “tin whistle” upper voice extension is due to segmental vibration is by videostroboscopic examination during that kind of phonation. The other way is for the individual to produce their “tin whistle” kind of voice very softly and then try to crescendo. If full length vibration, smooth crescendo will be possible. If segmental, there will be a sudden “squawk” as the vocal cords try to go (unsuccessfully) from segmental to full-length vibration.
Segmental Vibration Compared to Full-length
Translucent polypoid swellings (1 of 4)
A younger man with chronic hoarseness due to large translucent polypoid swellings, not seen well at closed phase of full-length vibration at E3 (165 Hz).
Open phase, E3 (2 of 4)
Open phase of vibration at the same pitch showing that the full length of both cords swings laterally. Now the large polyp left vocal cord (right of photo) is easily seen.
Closed phase, E4 (3 of 4)
At E4 (330 Hz), vibration is damped (not allowed) except for the short anterior segment indicated by arrows.
Open phase, E4 (4 of 4)
At the same pitch, but open phase of vibration of that same short segment.
Whistle Register or Tin-whistle Segmental Vibration?
Closed phase (1 of 4)
Closed phase of vibration at C4 (~ 262Hz) in a woman who is chronically hoarse and is a “vocal overdoer”. Note the early contact at the bilateral swellings (right greater than left), and the MTD posturing (separation of vocal process “grey” zone posteriorly).
Open phase (2 of 4)
Open phase of vibration, shows that the entire length of the vocal cord margin participates in vibration at this pitch.
Segmental vibration (3 of 4)
Segmental vibration at F5 involves only the short anterior segment (brackets). The vocal cord swellings do not vibrate, nor does the posterior vocal cord. This is the closed phase of vibration.
Whistle register (4 of 4)
Open phase of that tiny anterior segment. This imparts a truly tiny “tin whistle” quality that cannot be maximized to a volume above beyond pianississimo. In some cases, singers who have not seen their vocal cords at this kind of high magnification under strobe light believe this to be a normal “whistle register”.
Search not Only for Nodules, but Also for Segmental Vibration and Look at the Posterior Commissure for MTD
Open phase (1 of 4)
In a young pop-style singer, the open phase of vibration under strobe light at C#5 (554 Hz). This magnified view is best to see the large fusiform nodules.
Closed phase (2 of 4)
Closed phase of vibration at the same pitch shows touch closure—that is, that the nodules barely come into contact.
Segmental vibration (3 of 4)
Even when patients are grossly impaired in the upper voice as is the case here, the clinician always requests an attempt to produce voice above G5 (784 Hz), in order to detect segmental vibration. Here, the pitch suddenly breaks to a tiny, crystal-clear D6 (1175 Hz) Only the anterior segment (arrows) vibrates.
Posterior commissure (4 of 4)
A more panoramic view that intentionally includes the posterior commissure to show that the vocal processes, covered by the more ‘grey’ mucosa (arrows), do not come into contact. This failure to close posteriorly is a primary visual finding of muscular tension dysphonia posturing abnormality.
Sulcus and Segmental Vibration
Glottic sulci (1 of 4)
Closed phase of vibration, strobe light, at G3 (196 Hz) in a young high school teacher/ coach who is also extremely extroverted. Faint dotted lines guide the eye to see the lateral lip of her glottic sulci.
Open phase (2 of 4)
Open phase of vibration at the same pitch, showing full-length oscillation.
Closed phase (3 of 4)
Closed phase of vibration at E-flat 5 (622 Hz). Arrows indicate closure of the short oscillating segment.
Segmental vibration (4 of 4)
Open phase of vibration also at E-flat 5, Only the tiny segment opens significantly. As expected the patient’s voice has the typical segmental “tin whistle” quality.
Open Cyst and Sulcus; Normal and Segmental Vibration
Margin swelling (1 of 6)
Breathing position of the vocal cords of a very hoarse actor. Note the margin swelling of both sides. The white material on the left vocal cord (right of photo) is keratin debris emerging from an open cyst. Find the sulcus of the right vocal cord (left of photo) which is more easily seen in the next photo.
Narrow band light (2 of 6)
Further magnified and under narrow band light. The right sulcus is within the dotted outline. Compare now with photo 1.
Open phase, strobe light (3 of 6)
Under strobe light, open phase of vibration at A3 (220 Hz). The full length of the cords participate in vibration.
Closed phase, same pitch (4 of 6)
At the same pitch, the closed phase again includes the full length of the cords.
Segmental vibration (5 of 6)
At the much higher pitch of C5 (523 Hz) a “tin whistle” quality is heard and only the anterior segment (at arrows) is opening for vibration. The posterior opening is static and not oscillating, as seen in the next photo.
Closed phase (6 of 6)
The closed phase of vibration involves only the tiny anterior segment of the vocal cords, at the arrows. The posterior segment is not vibrating and is unchanged.
Tiny Vibrating Segment Gives Tiny Tin Whistle Voice
Prephonatory instant (1 of 6)
This young woman has been hoarse for many years. This preparatory posture shows marked separation of the cords posteriorly, suggesting MTD as well.
Phonation (2 of 6)
Now producing voice, with vibratory blur of the entire length of the cords on both sides.
Gaps due to nodules (3 of 6)
Under strobe light at a lower pitch of A4 (440 Hz), closed phase of vibration. Large gaps anterior and posterior to the polypoid nodule(s) explain breathy quality and short phonation time.
Open phase (4 of 6)
Open phase of vibration also at A4 (440 Hz) shows that the full length of the vocal cords are vibrating. Compare with the following two photos.
“Tin whistle” sound (5 of 6)
Now at A5 (880 Hz), the patient can only make an extremely tiny (tin whistle) quality. The only segment vibrating is within the circle (here, closed phase). The posterior segment does not vibrate.
“Tin whistle” at open vibration (6 of 6)
Still at A5 (880 Hz), the open phase of vibration, again of *only* the tiny anterior segment.
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