An X-ray Study on the Level of the Vocal Fold During Phonation

In the laryngograms taken during phonation and respiration, the figure of the tracheal portion itself remains unchanged. When both laryngeal figures are superimposed at the tracheal portion, movement of the vocal fold in the laryngeal cavity can be quantitatively mesured. This method was applied to the observation of the level of the glottis during phonation. The larynx is elevated during phonation, but the vocal fold moves downward in the laryngeal cavity. Therefore, the vertical movement of the vocal fold is radiographically considered in two ways; movement relative to the surrouding tissue and absolute movement in the laryngeal cavity. The latter movement was discussed in this study.1) The level of the glottis during phonation is 3mm to 4mm lower than during respiration.2) In male subjects, the higher the pitch ascends, the lower the glottis descends in the same register. In female cases, the same phenomenon is found only in the range of low voice.3) At the same pitch, the level of the glottis during phonation of chest voice is lower than that of head voice.