The vocal folds act as gatekeeper to the flow of air into and out of the lower airway. Another function of the vocal folds is that of oscillating sound source. To date, research has shown that under high respiratory drive (HRD) conditions voice is breathy, suggesting respiratory function will be favored over voice as physiologic needs increase. The problem is for physically active voice users, acoustic goals are relatively fixed. This study used a “physiology of activity” paradigm within action theory to investigate the extent to which phonatory and respiratory functions may be affected by systemically varying vocal and metabolic goals. Thirty-two English-speaking females, ages 18-35 years, who were vocally untrained and recreationally active, participated in the study. Participants produced sets of seven consonant-vowel syllables, at rest, using a pre-determined pitch at a comfortable loudness and in a loud voice. Following, participants walked on a treadmill to achieve low and high workloads at established speed and grade adjustments. The same speech task was repeated, using the same vocal intensities. Order of vocal and exercise intensities were counterbalanced. In terms of phonatory function, Rlaw increased significantly more from a baseline of spontaneous voice at rest during loud voice compared to spontaneous voice, mediated by an increase in Ps. Moreover, Rlaw decreased significantly more from baseline with an increase in workload, resulting in increases in metabolic variables. The decrease in Rlaw coincided with numerical increases in airflow. Voice production, as compared to breathing, reduced Ve, interfering with gas exchange. No differences existed for metabolic variables between voice conditions. This study reflected an attempt to understand the impact of goal-oriented behavior on phonatory and respiratory functions during HRD by manipulating acoustic and metabolic goals. Consistent with prior research, voice, as opposed to breathing, resulted in airflow limitation during HRD, reducing ventilation and CO2 clearance. Extreme respiratory perturbations lead to decreases in phonatory function to support metabolic needs. As predicted by action theory, loud voice appeared to favor phonatory function when acoustic goal was specified, at least in the short term. Conversely, spontaneous voice demonstrated deference to respiratory function when acoustic goals remained unspecified
