Changes in Vocal Fold Morphology During Singing Over Two Octaves.

Objective: Vocal folds are widely assumed to only elongate to raise vocal pitch. However, the mechanisms seem to be more complex and involve both elongation and tensioning of the vocal folds in series. The aim of the present study was to show that changes in vocal fold morphology depend on vocal fold elongation and tensioning during singing.

Study Design: This was a prospective study.

Methods: Forty-nine professional female singers (25 sopranos, 24 altos) were recruited and three-dimensional laryngeal images analyzed in a coronal view derived from high-resolution computed tomography scans obtained at the mean speaking fundamental frequency (ƒ) and one (2ƒ) and two octaves (4ƒ) above ƒ.

Results: The vocal fold angle, defined by a tangent above and below the vocal folds, was 58° at ƒ, 47° at 2ƒ, and 59° at 4ƒ.

Conclusion: The decreased caudomedial angle of the vocal fold from ƒ to 2ƒ (change in muscle belly from ";fat" to "thin") and increased angle from 2ƒ to 4ƒ (from "thin" to "fat") strongly supports the hypothesis that the vocal folds elongate and then tension when singing from ƒ to 4ƒ. This is the first study to show this relationship in vivo.