Endolaryngeal changes during high-intensity phonation videolaryngoscopic observations

Using a five-part vocal figure and standard fiberoptic techniques, we have analyzed the laryngeal functions of a group of professional singers and have made five observations occurring during high-intensity phonation that contradict the accepted physiologic functioning of the larynx. We have analyzed these contradictions as they relate to the three endolaryngeal sphincters; this was accomplished by the development of a four-component vocal protocol to examine the changes in these laryngeal structures and the degree of independent control of each of these structures possible in this group of specialized subjects. We have attempted to explain our findings based on available data relating to the functions of the intrinsic and extrinsic laryngeal musculature (including the cricothyroideus muscle) and the neurologic mechanisms involved. Finally, we discuss this data as it relates to current vocal training.