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

This study examined the immediate effects of the Finger Kazoo (FK) exercise, with and without intentional oropharyngeal enlargement, on acoustic, self-perceptual, and auditory-perceptual parameters of the operatic singing voice.

Fifteen classically trained singers screened using the Singing Voice Handicap Index-10 performed two randomized conditions: FK without oropharyngeal enlargement (Condition A) and FK with oropharyngeal enlargement (Condition B). Assessments included: (1) self-perception using the Evaluation Auditory-Perceptual Instrument for Operatic Singing Voice-EAI Scale; (2) acoustic analysis of maximum phonation time (MPT) for vowels /a/ and /i/, examining fundamental frequency (F₀), jitter, and shimmer; and (3) blinded auditory-perceptual ratings of aria excerpts by a 15-member expert panel. Statistical procedures comprised paired and nonparametric tests (t, Wilcoxon, and Friedman), robust analyses, and Bayes factors, with Holm-adjusted P values and effect sizes (Cohen's d, r).

Both interventions significantly improved MPT and reduced jitter and shimmer (all p <.05), with very large effect sizes (Cohen's d > 0.8). Mean MPT increased by 12-15%, jitter decreased by 13-16%, and shimmer by 18-20%. F₀ remained stable across vowels and conditions (P > 0.59), indicating enhanced phonatory control without pitch alteration. Self-perception scores increased from baseline (38.5 ± 6.3) to post intervention (51.6 ± 13.6 in A; 53.9 ± 8.4 in B; P < 0.001). Auditory-perceptual ratings confirmed significant improvements across all eight EAI parameters-most notably Resonance Balance, Ring, Vibrato, and Pitch Accuracy-while Strain showed smaller but consistent reductions. No statistically detectable differences were found between Conditions A and B, with Bayesian analyses supporting equivalence (BF₁₀ < 1/3).

The FK exercise produced immediate, robust, and clinically meaningful improvements in resonance, stability, and efficiency of the operatic singing voice. Both versions-performed with and without oropharyngeal enlargement-were comparably effective, underscoring the versatility of this semioccluded vocal tract technique as an evidence-based tool for singers, pedagogues, and clinicians.