Divergent Neurophysiological Mechanisms Underlying 40 Hz, 528 Hz, And 432 Hz Sound Exposure: A Review of Biomarker Evidence in Anxiety and Depression

Abstract

Growing interest in non-pharmacological approaches to mental health has renewed scientific attention toward the therapeutic effects of sound. Within this expanding domain, specific frequencies such as 40 Hz, 528 Hz, and 432 Hz have attracted both popular and research-oriented curiosity, yet their biological and psychological effects remain unevenly understood. Anxiety and depression are complex conditions driven by interactions between neural oscillations, stress-endocrine pathways, autonomic regulation and affective circuitry, making biomarker-based investigations essential for understanding how acoustic stimuli may influence emotional health. This narrative review synthesises evidence on the biomarker-level effects of the three frequencies and highlights the distinct neurophysiological pathways through which each appears to operate.