Hemachandran Ravikumar, Suresh Sathyanarayanan
Background Psychological stress contributes to mental health symptoms and cardiovascular risk through pathways involving anxiety, depression, cortisol secretion, autonomic dysregulation, and elevated blood pressure. Sound-based meditation is a nonpharmacological approach that may support stress management, but randomized controlled trial evidence remains limited. Objective The objective was to evaluate whether a structured sound-based meditation intervention was associated with lower post-intervention anxiety symptoms, measured using the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A), than a remotely delivered music-control condition after four weeks. Depressive symptoms, salivary cortisol concentration, systolic blood pressure, and exploratory diastolic blood pressure were also assessed. Methodology This parallel-group randomized controlled trial enrolled 100 adults aged 21-65 years from meditation centers and surrounding communities in Tamil Nadu, India. Participants were randomly assigned in a 1:1 ratio to a sound-based meditation intervention group (n = 50) or a remotely delivered music-control group (n = 50). The intervention group attended supervised, face-to-face, 60-minute daily sound-based meditation sessions for four weeks, involving recorded 528-Hz audio and acoustic instruments, including singing bowls, gongs, bells, and tingshas. The control group attended supervised 60-minute Google Meet sessions using two standardized, licensed music tracks with scheduled silent intervals. The primary analysis used analysis of covariance (ANCOVA) to compare post-intervention HADS-A scores between groups, adjusted for baseline HADS-A scores. Corresponding ANCOVA models evaluated HADS-D, salivary cortisol, and systolic blood pressure as secondary outcomes; diastolic blood pressure was exploratory. Holm adjustment was applied across the five reported outcomes. Results Observed baseline characteristics were comparable between groups. In baseline-adjusted ANCOVA analyses, post-intervention HADS-A scores were lower in the intervention group than in the music-control group (adjusted mean difference = -2.55, 95% confidence interval (CI): -3.62 to -1.48; Holm-adjusted P < 0.001; partial η 2 = 0.19). Corresponding adjusted differences favored the intervention group for HADS-D (adjusted mean difference = -2.39, 95% CI: -3.36 to -1.43; Holm-adjusted P < 0.001; partial η 2 = 0.20), salivary cortisol (-2.54 nmol/L, 95% CI: -2.95 to -2.13; Holm-adjusted P < 0.001; partial η 2 = 0.61), systolic blood pressure (-7.62 mmHg, 95% CI: -9.36 to -5.89; Holm-adjusted P < 0.001; partial η 2 = 0.44), and exploratory diastolic blood pressure (-2.22 mmHg, 95% CI: -3.00 to -1.43; Holm-adjusted P < 0.001; partial η 2 = 0.24). No adverse events were reported. Conclusions This randomized controlled trial provides preliminary evidence that participation in a structured sound-based meditation program was associated with greater short-term improvements in anxiety, depression, salivary cortisol, systolic blood pressure, and exploratory diastolic blood pressure compared with a remotely delivered music-control condition. These findings should be confirmed in larger, fully standardized randomized controlled trials with longer follow-up and diverse populations.