The vocal pitch is controlled by the tension, mass, and length of the vocal fold. It is well known that cricothyroid approximation raises the vocal pitch by simulating the contraction of the cricothyroid muscle, and there were so many reports
that
have
noted a relationship between cricothyroid distance and pitch control, but there does not seem to be any single generally accepted theory to account for this connection. It is generally known that the strap muscles are active during low and
falling
Fo,
and the suprahyoid muscles are active during high and raising Fo. These findings can be related to a general picture of the motion of the larynx during changes in Fo, the cricothyroid joint would tend to lengthen the vocal folds, as the larynx
moves up
and forward, and relax them as it moves back and down.
In this study, we suggest that the relationship between anterior cricothyroid distance and fundamental frequency of the larynx was so complex according to the level of larynx and vertebral curvature. The higher the level of larynx, the wider the
cricothyroid distance, but there is more greater fundamental frequeny even though more wide cricothyroid distance. This phenomenon seems to be due to the multifactors, especially the vertical tension of the conus elasticus or the change of
cricothyroid
articulation. It is generally known that the crocothyoid and vocalis muscles are very closely related to pitch elevation, but sternohyoid muscle seems to be more closely related to pitch lowering, By this electromyographic studies, the
sternohyoid
muscle have dual activity to patch control, increased activity during the low fundamental frequency and falling pitch, but also increased activity during the higher fundamental frequency and raising pitch at least in this study.
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