NCT07129668

Effects of Finger Kazoo Exercise With and Without Oropharyngeal Enlargement in the Operatic Singing Voice

Effects of Finger Kazoo Exercise With and Without Oropharyngeal Enlargement in the Operatic Singing Voice: A Randomized, Single-Blind, Crossover Controlled Clinical Trial

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 15 (actual)
• Sponsor: Aveiro University · Academic / Other
• Sex: All
• Age: 18 Years – 55 Years
• Healthy volunteers: Accepted

Summary

This clinical trial aimed to evaluate the effects of the semi-occluded vocal tract exercise Finger Kazoo (FK), with and without oropharyngeal expansion, on the singing voice. Fifteen classically trained singers, screened using the Singing Voice Handicap Index-10 (SVHI-10), participated in a randomized, single-blind, crossover trial with two experimental sessions separated by 48 hours. Participants were randomized via Sealed Envelope to start in Condition A (without oropharyngeal expansion) or Condition B (with oropharyngeal expansion). In each session, standardized recordings were obtained before and after the intervention, including maximum phonation time for the vowels /a/ and /i/, and an operatic aria excerpt. Acoustic analysis (PRAAT) extracted fundamental frequency (F0), jitter, and shimmer. Comparisons between baseline and experimental conditions were performed using paired-samples t-tests, Wilcoxon tests, robust paired t-tests, and Friedman ANOVA with Durbin-Conover, Tukey, Bonferroni, and Holm post hoc corrections, with a 95% confidence interval. Auditory-perceptual evaluation was conducted by 15 blinded experts using the EAI Scale Form, with balanced sample distribution among raters. Self-perceptual evaluation was also performed by participants using the same scale.

Conditions

• Voice Alteration

Interventions

Type	Name	Description
BEHAVIORAL	Condition A	Condition A consists of performing the Finger Kazoo exercise without inducing oropharyngeal enlargement. In this condition, participants place the index finger vertically in front of the lips to partially occlude the vocal tract, producing a semi-occluded vocal tract configuration, but without modifying tongue position, soft palate height, or pharyngeal wall expansion to increase the oropharyngeal space.
BEHAVIORAL	Condition B	Condition B consists of performing the Finger Kazoo exercise with intentional oropharyngeal enlargement. In this condition, participants place the index finger vertically in front of the lips to partially occlude the vocal tract, producing a semi-occluded vocal tract configuration, while simultaneously modifying tongue position, elevating the soft palate, and expanding the pharyngeal walls to increase the oropharyngeal space.

Timeline

• Start date: 2025-05-30
• Primary completion: 2025-07-24
• Completion: 2025-07-26
• First posted: 2025-08-19
• Last updated: 2025-08-19

Locations

1 site across 1 country: Portugal