Acoustic analysis of vocal intensity and decision-making processes in national level soft tennis officiating: A mixed methods study

Introduction: The International Soft Tennis Federation mandates a "loud and clear" call for officiating; however, this requirement remains qualitatively abstract without empirical acoustic metrics. Objective: This study aimed to quantify the vocal intensity of the "out" call among national-level referees and elucidate the cognitive rationale underlying their vocal modulations. Methodology: An explanatory sequential mixed-methods design (QUAN → qual) was employed. Fifteen national-level referees (n = 15) participated in a controlled field simulation on a regulation Soft Tennis court to maintain ecological validity. Vocal intensity (dBA) was measured using a Class 2 sound level meter under three conditions: Appropriate (Baseline), Low, and High intensity. Subsequently, stimulated recall interviews were conducted with a subsample (n = 6) to explore decision-making processes. Results: Quantitative analysis revealed a significant hierarchy in vocal output, F (2, 28) = 53.891, p < .001, ( = .794), High-intensity calls yielded the highest mean (103.83 ± 5.54 dB), while low-intensity calls (93.69 ± 3.39 dB) were significantly lower than the baseline (98.33 ± 4.23 dB). Discussion: The findings suggest that vocal intensity is not a static physical requirement but a dynamic strategic instrument. High intensity serves as a "psychological wall" for conflict management during close calls, whereas low intensity reflects "social etiquette" and empathy during obvious errors. Conclusions: Referees modulate their voice based on situational demands. These findings transition officiating standards from abstract mandates to measurable acoustic benchmarks, advocating for the integration of vocal competency into referee certification programs.