Resonant Breathwork as Multimodal Vagal–Interoceptive Modulation: An Empirical Synthesis of Non-invasive VNS, Breathing-Driven Interoception and Respiratory Tools

Abstract: Resonant Breathwork is proposed as a layered, measurable intervention that modulates vagal activity and interoceptive processing through acoustic vocalization, respiratory mechanics, and biofeedback. This review synthesizes human empirical studies from 2022–2025 across five domains: (1) noninvasive transcutaneous auricular vagus nerve stimulation and acoustic or vocal vagal engagement; (2) interoception targets modulated by breathing; (3) respiratory rehabilitation tools, including oscillatory positive expiratory pressure and inspiratory muscle training; (4) virtual or augmented reality breath biofeedback; and (5) neuroimaging of high ventilation breathwork with music. Evidence shows taVNS can acutely increase vagal indices, with effects contingent on frequency and pulse width, while paced humming or singing near 0.1 Hz enhances respiratory sinus arrhythmia and positive affect. Breathing phase shapes perception and neural excitability; exhalation weighting and slow pacing amplify heartbeat evoked potentials and attention to internal signals. OPEP improves airway clearance and symptoms, and inspiratory training increases inspiratory strength with shifts toward parasympathetic balance, suggesting autonomic co benefits beyond pulmonary gains. XR delivery yields physiologic outcomes comparable to non XR biofeedback but improves engagement and transfer in stress laden contexts. Neuroimaging during high ventilation plus music reveals reduced perfusion in interoceptive cortex and increased perfusion in limbic regions alongside sympathetic activation and post session emotional relief. Findings align with a testable framework in which acoustic resonance, mechanical load, and feedback guided timing jointly modulate vagal efference and interoceptive circuitry, with translational potential for neurodivergent and post viral dysautonomia.