Immediate Effects of Voiced High-Frequency Oscillation with Two Resistance Levels on the Vocal Function of Women with...

This study aimed to verify and compare the immediate effects of voiced high-frequency oscillation (VHFO) performed with two resistance levels on aerodynamic, acoustic, vocal economy, and vocal self-assessment measures in women with behavioral dysphonia.

This was a randomized, crossover, immediate-effect experimental study. Thirty cisgender women aged 18 to 50 years (mean = 32.6 ± 9.07) with behavioral dysphonia participated in this study. Then, all participants performed VHFO for three minutes using the New Shaker® (resistance: 11cmH₂O) and Shaker Medic Plus® (resistance: 4cmH₂O) devices, with a minimum washout of two days between applications. Assessments conducted before and after each condition included aerodynamic measures (transglottic airflow, glottic resistance, subglottic pressure, oral pressure, transglottic pressure, and phonation threshold pressure), vocal economy (Quasi-Output-Cost Ratio and its components), acoustics (Cepstral Peak Prominence Smoothed - CPPS, Acoustic Voice Quality Index - AVQI, and Acoustic Breathiness Index - ABI), and vocal self-assessment (vocal comfort, vocal quality, and respiratory comfort during speech). Data were analyzed using repeated measures ANOVA (P<0.05) and Tukey test.

Both resistance levels significantly reduced glottic resistance (P<0.001), subglottic pressure (P=0.018), and transglottic pressure (P=0.005), as well as increased transglottic airflow (P<0.001). There was also an improvement in self-assessment of vocal comfort, vocal quality, and respiratory comfort during speech (P<0.001), with no difference between the resistance levels (P>0.05). However, only the higher resistance level generated positive effects on acoustic parameters: an increase in CPPS (P=0.026) and a reduction in AVQI values (P=0.002), as well as increased vocal economy with a reduction in the glottic contact quotient (P<0.001).

VHFO produced immediate positive effects on aerodynamic measures and vocal self-assessment, regardless of resistance level in women with behavioral dysphonia. In contrast, only the highest resistance level yielded immediate positive effects on vocal economy and acoustic parameters of vocal quality.