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

NCT ID: NCT07129668

Last Updated: 2025-08-19

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 15 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-05-30
• Study Completion Date: 2025-07-26

Brief 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

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: HEALTH_SERVICES_RESEARCH
• Blinding Strategy: NONE

Study Groups

Condition A

Without Oropharyngeal Enlargement

Group Type: ACTIVE_COMPARATOR

Condition A

Intervention Type: BEHAVIORAL

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.

Condition B

Intervention Type: BEHAVIORAL

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.

Condition B

With Oropharyngeal Enlargement

Group Type: ACTIVE_COMPARATOR

Condition A

Intervention Type: BEHAVIORAL

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.

Condition B

Intervention Type: BEHAVIORAL

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.

Condition 0 or Baseline

Condition 0 (Baseline) consists of producing the target vocal tasks without any semi-occlusion or intentional oropharyngeal modification just a pre vocal warmup.

Group Type: ACTIVE_COMPARATOR

Condition A

Intervention Type: BEHAVIORAL

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.

Condition B

Intervention Type: BEHAVIORAL

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.

Interventions

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.

Intervention Type: 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.

Intervention Type: BEHAVIORAL

Other Intervention Names

Whitout Oropharyngeal Enlargement; With Oropharyngeal Enlargement

Eligibility Criteria

Inclusion Criteria

• Classically trained singers aged 18 to 45 years.
• Scoring below the cutoff for vocal handicap on the Singing Voice Handicap Index-10 (SVHI-10 ≤ 6 )*.
• No history of recently vocal fold pathology or laryngeal surgery.
• Non-smokers and no current upper respiratory infection.
• Willingness and ability to attend two experimental sessions spaced 48 hours apart.

Exclusion Criteria

• Presence of any current voice disorder or history of chronic laryngeal disease.
• Recent respiratory infection within 2 weeks prior to enrollment.
• Use of medications affecting voice or respiratory function.
• Inability or unwillingness to comply with study protocol.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 55 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

School of Health Sciences, University of Aveiro (ESSUA)

UNKNOWN

Sponsor Role: collaborator

Aveiro University

OTHER

Sponsor Role: lead

Responsible Party

Jean Carlos Gorges

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Essua - University of Aveiro

Aveiro, Aveiro District, Portugal

Countries

Portugal

Other Identifiers

doi.org/10.54499/2023.0361.BD

Identifier Type: OTHER_GRANT

Identifier Source: secondary_id

10-CE/2025

Identifier Type: -

Identifier Source: org_study_id