Investigating the Relationship Between Maximum Phonation Time of Different Vowel Sounds and Respiratory Function

Spirometry testing, while effective, presents challenges including accessibility, cost, and patient cooperation requirements. Alternative methods for assessing respiratory function are needed. The aim of this study is to investigate whether the maximum phonation time (MPT) of different vowel sounds can serve as a reliable indicator of respiratory function in healthy young adults.

This cross-sectional study included 83 healthy individuals (64 female, 19 male) aged 20-25 years. Respiratory function was assessed using standard spirometry measurements, including forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), FEV₁/FVC%, peak expiratory flow rate (PEFR), and forced expiratory flow at 25%-75% of the pulmonary volum (FEF_25%-75%). MPT were measured for eight vowel sounds (A, E, I, İ, O, Ö, U, Ü). Relationships between MPT and spirometry measurements were analyzed using correlation and regression analyses.

The study found that two vowels influenced FEV₁. One-second increase in phonation time of the "A" sound corresponded to a 0.060 L increase in FEV₁ (P < 0.002), while the "Ü" sound showed a smaller but significant effect of 0.038 L per second (P < 0.036). For FVC, only the "A" sound showed a significant effect, with 1-second increase in phonation time associated with a 0.040 L increase in FVC (P < 0.002). Similarly, PEFR was uniquely affected by the "Ü" sound, demonstrating a 0.098 L increase per second of phonation time (P < 0.001). The FEV₁/FVC ratio showed no significant associations with any vowel sounds (all P > 0.19). In terms of small airway function, the "A" sound emerged as the sole significant predictor of FEF_25%-75%, with 1-second increase in phonation time corresponding to a 0.048 L increase (P < 0.010).

The MPT of the vowel's "A" and "Ü" shows promise as a simple and effective tool for screening respiratory function. While the "A" sound is phonetically comparable across many languages, including English, the "Ü" sound's potential as a respiratory function indicator may be more relevant to languages with similar phonetic structures. This non-invasive approach could reduce healthcare costs and improve access to respiratory assessments, particularly in resource-limited settings or for remote monitoring, though caution is needed when applying the findings to non-Turkish-speaking populations.