Development and Initial Validation of Phonation Quotient for Connected Speech: A Low-Cost, Indirect Aerodynamic...

The phonation quotient derived from a sustained vowel (PQ-SV) is a valid, low-cost estimate of phonatory airflow but may not reflect the aerodynamic demands of connected speech. This study introduces the phonation quotient for connected speech (PQ-CS), a novel extension of PQ-SV, and evaluates its initial validity by examining (1) the relationship between PQ-CS and directly measured airflow during connected speech; (2) physiologic relationships among PQ-CS component measures; and (3) whether PQ-CS or PQ-SV demonstrates stronger associations with airflow across connected speech and sustained vowel tasks.

Thirty adults without structural laryngeal pathology completed vital capacity maneuvers; comfortably spoken and maximum phonation of a sustained vowel (/a/); and comfortably spoken and maximum phonation of continuously repeated productions of the voiced sentence "We were away a year ago." Time, volume, and airflow were measured using the Phonatory Aerodynamic System. PQ-CS and PQ-SV were calculated as vital capacity divided by maximum phonation time for the connected speech and sustained vowel tasks, respectively. Associations were evaluated using simple linear regression and Pearson correlation coefficients.

PQ-CS demonstrated significant positive associations with mean flow rate during both the maximum phonation connected speech task (r = 0.57) and the comfortably spoken connected speech task (r = 0.41). PQ-CS component measures exhibited expected physiologic relationships, including strong associations between vital capacity and phonation volume (r = 0.62) and a negative association between task duration and mean flow rate (r = -0.37). Across connected speech tasks, PQ-CS showed stronger associations with airflow than PQ-SV. In contrast, PQ-SV demonstrated the strongest association with airflow during maximum sustained vowel phonation, whereas PQ-CS showed a stronger association during comfortably sustained vowel production.

PQ-CS is a valid, physiologically grounded, and clinically feasible indirect measure of phonatory airflow during connected speech. Together, PQ-CS and PQ-SV provide complementary aerodynamic information that may enhance clinical voice assessment when specialized equipment is unavailable.