Objective: To verify and compare the immediate effects of Voiced Oral High-Frequency Oscillation (VOHFO) performed with two resistance levels on aerodynamic, acoustic, vocal economy, and self-evaluation measures in women with behavioral dysphonia.
Methods: This immediate-effect, randomized, crossover experimental study (IRB: 6.646.676) included 30 cisgender women aged 18–50 years (mean = 32.6 ± 9.07) diagnosed with behavioral dysphonia associated with benign vocal fold lesions or glottal gaps. Each participant performed VOHFO for three minutes with the New Shaker® (resistance: 11 cmH₂O) and Shaker Medic Plus® (resistance: 4 cmH₂O), with a minimum two-day washout. Pre- and post-task assessments included aerodynamic measures (transglottal airflow, glottal resistance, subglottal, oral, and transglottal pressures, and phonation threshold pressure), vocal economy (Quasi-Output-Cost Ratio and components), acoustic parameters (Cepstral Peak Prominence Smoothed – CPPS, Acoustic Voice Quality Index – AVQI, Acoustic Breathiness Index – ABI), and vocal self-evaluation (comfort, vocal quality, and speech-related breathing). Data were analyzed using repeated-measures ANOVA (p<0.05) and Tukey tests.
Results: Both resistance levels significantly reduced glottal resistance (p<0.001), subglottal pressure (p=0.018), and transglottal pressure (p=0.005), and increased transglottal airflow (p<0.001). Participants also reported improved comfort, vocal quality, and speech breathing (p0.05). However, only the higher resistance produced positive acoustic effects, including increased CPPS (p=0.026) and reduced AVQI (p=0.002), and improved vocal economy, evidenced by reduced Glottal Contact Quotient (p<0.001).
Conclusion: VOHFO generates immediate beneficial effects on aerodynamic and self-evaluation measures regardless of resistance level in women with behavioral dysphonia. Only the higher resistance condition produced additional immediate improvements in vocal economy and acoustic measures of vocal quality.