Introduction: Unilateral Vocal Fold Paralysis (UVFP) causes dysphonia to varying degrees, ranging from mild to severe, with a range of acoustic and perceptual symptoms necessitating voice therapy to improve voice quality using all possible intact phonatory aspects. Semi-occluded vocal tract exercises (SOVTE) are known for their improved vocal output, which is attributed to increased intraoral pressure. Modifying source-filter interaction leads to better glottal closure, vocal fold vibration, and subglottal air pressure. Few studies investigated these therapeutic approaches for UVFP, but we still need to know more about the long-term effects and the curse of this approach on UVFP. Since Thyroidectomy is one of the most frequent etiologies for UVFP, and most physicians prefer to postpone remediation surgeries up to one year after onset, we focused on these patients. So, in this study, we aimed to investigate the immediate and long-term effects of SOVTE on patients with UVFP by measuring acoustic parameters, perceptual properties, and patients’ self-evaluation using the VAPP-P.
Methods:
This is a clinical trial—patients are recruited based on Stroboscopy and perceptual assessment by an ENT and an SLP to be diagnosed as Unilateral Vocal Fold Paralysis one month after Thyroidectomy. Patients who had received an established diagnosis were assessed at baseline, immediately after treatment completion, and one month later using the VAPP-P questionnaire, as well as text reading, spontaneous speech, and vowel prolongation as voice samples. All the patients received 10 voice therapy sessions on a bi-weekly basis. Lip Trill, Tube Phonation, Humming, and Hand-over-Mouth were introduced according to a pre-designed treatment regimen to ensure consistency in the treatment plan for all patients. Praat software used to analyze the acoustic parameters, including Fundamental Frequency, Harmonic-to-Noise-Ratio, Jitter, Shimmer, and CPPs. Perceptual evaluation is also done based on GRBAS.
Results:
The study has recently finished, and the acoustic analysis is still ongoing. The GRBAS results showed that voice samples improved significantly in terms of Breathiness severity and Asthenia. The VAPP-P results indicated that, based on the repeated-measures test, patients experienced better VAPP-P scores over time (P < 0.05). However, the final results will be extracted soon.

Conclusion:
Preliminary results showed that SOVTE has effectively increased voice quality in patients with UVFP immediately, and the effect is maintained a month after treatment termination. However, cautiously, we can recommend SOVTE as an option for patients with UVFP immediately after the first diagnosis to improve their voice quality very soon.