Voice AlterationFIKVOXNCT07129668
Effects of Finger Kazoo Exercise With and Without Oropharyngeal Enlargement in the Operatic Singing Voice
A study testing Condition A and Condition B in people with Voice Alteration, run by Aveiro University at 1 site in Portugal.
Trial 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… Read more about this study
- Who is it for?
- Ages 18 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Voice Alteration
- What is being tested?
- Condition A and Condition B
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 1 sitePortugal
- Study dates
- 30 May 2025to 26 Jul 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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.
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country.
Portugal1 site
Essua - University of Aveiro
Aveiro, Aveiro District, 3810-193
About this study
Official title: Effects of Finger Kazoo Exercise With and Without Oropharyngeal Enlargement in the Operatic Singing Voice: A Randomized, Single-Blind, Crossover Controlled Clinical Trial
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
- Being tested
- Condition A, Condition B
- Keywords
- Singing Voice, Finger Kazoo, SOVTE, Operatic Voice
- Medical subject headings
- Dysphonia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Condition ABehavioural
Also called Whitout Oropharyngeal Enlargement
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 BBehavioural
Also called With Oropharyngeal Enlargement
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.
| Study group | Role | What they receive |
|---|---|---|
| Condition A | Active comparator | Without Oropharyngeal Enlargement Receives: Behavioral: Condition A; Behavioral: Condition B |
| Condition B | Active comparator | With Oropharyngeal Enlargement Receives: Behavioral: Condition A; Behavioral: Condition B |
| Condition 0 or Baseline | Active comparator | Condition 0 (Baseline) consists of producing the target vocal tasks without any semi-occlusion or intentional oropharyngeal modification just a pre vocal warmup. Receives: Behavioral: Condition A; Behavioral: Condition B |
What is being measured
The primary outcome is the main question the study is designed to answer.
Maximum Phonation Time (MPT) variation between conditions without and with oropharyngeal enlargement.
Assessment of the difference in maximum phonation time (in seconds) between two experimental conditions: without oropharyngeal enlargement (Condition A) and with oropharyngeal enlargement (Condition B), during sustained vowel phonation.
Data Collection Method: Acoustic recordings obtained using Praat software. The MPT was measured from the onset of phonation to cessation, with participants instructed to sustain the vowel at comfortable pitch and loudness.
Analysis Method: Robust Paired Samples T-Test comparing MPT between Condition A and Condition B. Effect sizes calculated using Cohen's d. Results Summary: Mean MPT was significantly higher in Condition B (+7.9 s; p < .001; d = 0.46), indicating improved phonatory efficiency.
Measured: Baseline and 48 hours after first session (allowing return to baseline before second session).
Secondary outcomes (1)
Change in Fundamental Frequency Stability (ΔF0) between conditions without and with oropharyngeal enlargement.
Evaluation of the mean variation in fundamental frequency (in Hz) from onset to end of sustained vowel phonation, comparing Condition A and Condition B.
Data Collection Method: Praat software pitch analysis, extracting F0 mean values for initial and final 3 seconds of the sustained vowel, then calculating the difference (ΔF0).
Analysis Method: Robust Paired Samples T-Test. Results Summary: ΔF0 was significantly lower in Condition B (-7.6 Hz; p < .001; d = 0.39), indicating greater pitch stability.
Measured: Baseline and 48 hours after first session (allowing return to baseline before second session).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Aug 2025
- Study start30 May 2025
- Primary completion24 Jul 2025
- Study completion26 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Voice AlterationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Health services research
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Fifteen classically trained singers participated in a randomized, single-blind, crossover trial with two experimental sessions separated by 48 hours. Participants were allocated via Sealed Envelope randomization to start in Condition A (without oropharyngeal expansion) or Condition B (with oropharyngeal expansion). In each session, standardised recordings were obtained before and after the intervention, including maximum phonation time for the vowels /a/ and /i/, and an operatic aria excerpt.
- Masking
- None (open label)
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- Aveiro University
- Sponsor type
- University, hospital or other
- Collaborators
- School of Health Sciences, University of Aveiro (ESSUA)
- Responsible party
- Principal investigator, Jean Carlos Gorges, Aveiro University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07129668
- Sponsor's protocol ID
- 10-CE/2025
- Other IDs
- doi.org/10.54499/2023.0361.BD
- Acronym
- FIKVOX
- Status last verified
- Aug 2025
- First submitted
- 11 Aug 2025
- Last updated
- 19 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared due to institutional and legal restrictions on data privacy and protection as per the data protection agreement signed with the University of Aveiro.
Study at a glance
From the registry record, last updated by the sponsor on 19 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Finger Kazoo Exercise With and Without Oropharyngeal Enlargement in the Operatic Singing Voice: A Randomized, Single-Blind, Crossover Controlled Clinical Trial
- ClinicalTrials.gov ID
- NCT07129668
- Acronym / sponsor ID
- FIKVOX / 10-CE/2025
- Conditions
- Voice Alteration
- Keywords
- Singing Voice, Finger Kazoo, SOVTE, Operatic Voice
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 15 participants (actual)
- Lead sponsor
- Aveiro UniversityUniversity, hospital or other
- Collaborators
- School of Health Sciences, University of Aveiro (ESSUA)
- Study start
- 30 May 2025 (actual)
- Primary completion
- 24 Jul 2025 (actual)
- Study completion
- 26 Jul 2025 (actual)
- First posted
- 19 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Health services research
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- Fifteen classically trained singers participated in a randomized, single-blind, crossover trial with two experimental sessions separated by 48 hours. Participants were allocated via Sealed Envelope randomization to start in Condition A (without oropharyngeal expansion) or Condition B (with oropharyngeal expansion). In each session, standardised recordings were obtained before and after the intervention, including maximum phonation time for the vowels /a/ and /i/, and an operatic aria excerpt.
| Arm | Type | Receives |
|---|---|---|
| Condition A | Active comparator | Behavioral: Condition A, Behavioral: Condition BWithout Oropharyngeal Enlargement |
| Condition B | Active comparator | Behavioral: Condition A, Behavioral: Condition BWith Oropharyngeal Enlargement |
| Condition 0 or Baseline | Active comparator | Behavioral: Condition A, Behavioral: Condition BCondition 0 (Baseline) consists of producing the target vocal tasks without any semi-occlusion or intentional oropharyngeal modification just a pre vocal warmup. |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- 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.
Key exclusion criteria (4 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Condition AAlso: Whitout Oropharyngeal EnlargementCondition 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. | Behavioural | Condition 0 or Baseline, Condition A, Condition B |
| Condition BAlso: With Oropharyngeal EnlargementCondition 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. | Behavioural | Condition 0 or Baseline, Condition A, Condition B |
Primary outcome
Maximum Phonation Time (MPT) variation between conditions without and with oropharyngeal enlargement.
Time frame: Baseline and 48 hours after first session (allowing return to baseline before second session).
Assessment of the difference in maximum phonation time (in seconds) between two experimental conditions: without oropharyngeal enlargement (Condition A) and with oropharyngeal enlargement (Condition B), during sustained vowel phonation. Data Collection Method: Acoustic recordings obtained using Praat software. The MPT was measured from the onset of phonation to cessation, with participants instructed to sustain the vowel at comfortable pitch and loudness. Analysis Method: Robust Paired Samples T-Test comparing MPT between Condition A and Condition B. Effect sizes calculated using Cohen's d. Results Summary: Mean MPT was significantly higher in Condition B (+7.9 s; p < .001; d = 0.46), indicating improved phonatory efficiency.
1 secondary outcome
Change in Fundamental Frequency Stability (ΔF0) between conditions without and with oropharyngeal enlargement.
Time frame: Baseline and 48 hours after first session (allowing return to baseline before second session).
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 19 Aug 2025.
- Individual participant dataSharing planned: No. Individual participant data will not be shared due to institutional and legal restrictions on data privacy and protection as per the data protection agreement signed with the University of Aveiro.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Condition A and Condition B in people with Voice Alteration, run by Aveiro University at 1 site in Portugal.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 19 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Portugal. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Maximum Phonation Time (MPT) variation between conditions without and with oropharyngeal enlargement. (time frame: Baseline and 48 hours after first session (allowing return to baseline before second session).). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 Aug 2025.