Using a Vortex Whistle System to Estimate Phonatory Airflow via the Phonation Quotient

The primary purpose of this study was to examine the relationship between phonation quotient (PQ) obtained using a low-cost vortex whistle system (VWS) vs phonatory airflow (PA) in sustained voicing calculated using a clinical-standard pneumotach-based system (the Phonatory Aerodynamic System [PAS]). PQ values obtained using the VWS were also compared with PQ values obtained using a "gold" standard pneumotach-based Koko Sx1000 spirometer.

Participants were 91 vocally healthy young adults (61 females and 30 males) between the ages of 18 and 30 years. Measures of vital capacity (VC) were obtained using the VWS and Koko Sx1000 spirometer, and measures of maximum phonation time (MPT) and PA during sustained phonation were obtained from the Maximum Sustained Phonation protocol on the PAS. PQs were calculated via PQ = VC (L)/MPT (s).

Correlations of r = 0.828 and r = 0.791 were observed between PA and PQ_Koko and PQ_VWS, respectively, with no significant difference between the two correlations. Stronger correlations between both PQ_Koko and PQ_VWS and PA were observed in males vs females. Linear regressions to predict PA from either PQ_Koko or PQ_VWS resulted in residual standard errors of 0.037 L/s (37 mL/s) and 0.040 L/s (40 mL/s), respectively. PQ_VWS and PQ_Koko were highly correlated (r = 0.961).

These results confirm prior research demonstrating that PQ may be used as a reasonable substitute for PA, with error values within previously reported expected ranges of intrasubject variability. In addition, a low-cost VWS can provide similarly accurate measures of PQ vs those computed using VC estimates from a "gold standard" pneumotach-based spirometer. PQ estimates of airflow via a VWS show great promise as a low-cost method that can promote the use of respiratory measures of capacity and flow to the voice assessment protocols of speech-language pathologists.