Abstract
The mechanism of vocal cord vibration was investigated with excised larynges of men and dogs. High speed motion pictures of the vibrating vocal cord were taken not only from the above, but also from the side and the below. Careful observation and frame-by-frame analysis of the pictures led to the following conclusions:
1. The vocal cord, which has been set in paramedian position, begins to vibrate with an outward movement. This suggests that the roll of Bernoulli effect is not important to the vocal cord vibration.
2. Prior to the onset of vibration, the vocal cord and mucosa of the subglottic space are pushed upwards and outwards by an increasing subglottic pressure. There develops a mucosal ridge between the vocal cord and the subglottic space. The ridge does not vibrate noticeably. Movement of the subglottic mucosa appears not essential to the vocal cord vibration. It is the portion upper to the mucosal ridge where wave-like movements of the mucosa occurs
3. The vocal cord vibration is no other than periodic repetitions of wavelike movements of the glottal mucosa. A given point on the mucosa presents three-dimensional elliptic motion during vibration of the vocal cord.
4. There are differences in phase of movement between the upper and lower portion of the vibrating vocal cord.
