Objective: To develop the Vocal Conditioning Index for Singing Voice (VCI–Singing).
Methods: This methodological study followed the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. The initial phase focused on the theoretical definition and operationalization of the construct “vocal conditioning,” following Pasquali’s (1998) three-pole model for scale development (theoretical, empirical, and analytical). Constitutive and operational definitions were developed through a literature review, expert consultation, and synthesis of empirical evidence. Items were constructed and organized into dimensions derived from theoretical frameworks.
Results: The structured definition agreed upon by the authors is that vocal conditioning represents a systematic process of optimizing the physiological, biomechanical, acoustic, and aerodynamic capacities involved in voice production. Its goal is to promote efficient vocal use, enabling individuals to meet communicative or artistic demands with high performance, stability, and economy of effort. It enhances endurance and strength, improves pneumophonoarticulatory coordination, and optimizes muscular responses of the larynx and vocal tract under demand. Additionally, it mitigates vocal and mental fatigue, reduces the risk of overload-related injury, and facilitates faster recovery after intense vocal use. For operationalization within the VCI–Singing, the construct was divided into seven dimensions: (1) Endurance, (2) Strength, (3) Flexibility, (4) Velocity, (5) Agility, (6) Pneumophonoarticulatory Coordination, and (7) Equilibrium. The initial instrument consisted of 46 items distributed across seven corresponding blocks: endurance (10 items), strength (4 items), flexibility (9 items), velocity (3 items), agility (6 items), coordination (8 items), and equilibrium (6 items). Content validity procedures will be conducted through expert review using the Content Validity Index (CVI ≥ 0.78).
Conclusion: The VCI–Singing is the first PROM specifically developed to measure vocal conditioning in singers. Integrating theoretical precision, empirical foundations, and psychometric rigor, it establishes a comprehensive framework for future validation and application in both clinical and research settings in voice science.