Chapter three, “Vibratory Vagus Nerve Stimulation” from the recently released book, Sing and Shout for Health, Scientific Insights and Future Directions for Vocology explores the relationship between the vagus nerve, vocalization, vibratory stimulation, and the autonomic nervous system. The chapter provides a comprehensive overview of the vagus nerve, its anatomical relevance, and its role in the parasympathetic nervous system. The tenth cranial nerve, commonly known as the vagus nerve, is the primary component of the parasympathetic nervous system and is responsible for regulating various autonomic functions such as heart rate, digestion, and respiration (Waxenbaum et al., 2024). As the longest nerve in the body, it travels from the medulla oblongata through the neck, thorax, and abdomen, innervating key organs and systems (Breit et al., 2018).

The chapter explores vagus nerve stimulation and its relationship to vocalization. Research indicates that vocal practices such as chanting and humming can stimulate the vagus nerve, enhancing parasympathetic nervous system activity. For example, studies on the yogic practice of OM chanting have demonstrated its effectiveness in increasing heart rate variability (HRV) and promoting autonomic balance (Inbaraj et al., 2022). Similarly, the practice of Bhramari pranayama, or humming bee breath, has been found to positively impact HRV and vagal tone (Latha & Lakshmi, 2022).

The chapter also examines the impact of external, non-invasive vagus nerve stimulation (nVNS) techniques, such as transcutaneous auricular VNS (taVNS), which have shown therapeutic potential in treating conditions like stress, anxiety, and migraines (Goggins et al., 2022; Yap et al., 2020). Devices such as the gammaCore Sapphire and VeRelief by Hoolest have been authorized by the FDA for conditions exacerbated by COVID-19, demonstrating their clinical relevance (electroCore, 2024; Romaniw, 2020). Other non-invasive methods such as cold exposure, physical exercise, and myofascial release have also been considered as potential vagus nerve stimulants (Miller, 2023).

In contrast, internal, invasive vagus nerve stimulation (VNS), used to manage medical conditions such as epilepsy and depression, may have adverse effects on vocal function. Research indicates that implanted VNS devices can lead to changes in vocal quality, including increased hoarseness and breathiness (Saibene et al., 2020; Van Lierde et al., 2015).

Polyvagal Theory, proposed by Stephen Porges, provides a theoretical framework for understanding the vagus nerve’s role in emotional regulation and social engagement. According to this theory, activities such as singing can promote a “ventral vagal” state, enhancing feelings of safety and social connectivity (Porges, 2017). This perspective has been widely adopted in therapeutic practices.

Lastly, the chapter outlines practical exercises aimed at enhancing vagus nerve function. Techniques such as humming, paced breathing, and specific physical exercises have been shown to improve autonomic regulation and vocal health (Goldman & Goldman, 2017; Boone, 2016; Rosenberg, 2017).

ðREFERENCES

1. Boone, Daniel R. (2016). Is Your Voice Telling on You? How to Find and Use Your Natural Voice, Third Edition. San Diego, CA: Plural Publishing, Inc. ISBN 9781597569453.
2. Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Frontiers in Psychiatry, 9, 44. https://doi.org/10.3389/fpsyt.2018.00044
3. electroCore. (2024). electroCore | Pioneers of tech. stimulators of life. electroCore, Inc. https://www.gammacore.com
4. Goggins, E., Mitani, S., & Tanaka, S. (2022). Clinical perspectives on vagus nerve stimulation: present and future. Clinical Science (1979), 136(9), 695–709. https://doi.org/10.1042/CS20210507
5. Goldman, J., & Goldman, A. (2017). The Humming Effect. Simon and Schuster.
6. Inbaraj, G., Rao, R., Ram, A., et al. (2022). Immediate effects of OM chanting on heart rate variability measures compared between experienced and inexperienced yoga practitioners. International Journal of Yoga, 15(1), 52–58. https://doi.org/10.4103/ijoy.ijoy_141_21
7. Latha, R., & Lakshmi, S. S. (2022). A study on the immediate and training effects of Bhramari pranayama on heart rate variability in healthy adolescents. Biomedicine, 42(4), 784-788. https://doi.org/10.51248/.v42i4.1501
8. Porges, S. W. (2017). The Pocket Guide to Polyvagal Theory: The Transformative Power of Feeling Safe. W.W. Norton & Co.
9. Romaniw, M. (2020). U.S. Food and Drug Administration letter of authorization. FDA. https://www.fda.gov/media/139967/download
10. Rosenberg, S. (2017). Accessing the Healing Power of the Vagus Nerve: Self-help Exercises for
11. Anxiety, Depression, Trauma, and Autism. Berkeley, CA. North Atlantic Books.
12. Saibene, A. M., Fuccillo, E., Felisati, G., et al. (2020). Vocal Outcomes in Vagus Nerve Stimulation: A Laryngeal Pattern-Based Objective Analysis. Journal of Voice, 36(5), 719–725. https://doi.org/10.1016/j.jvoice.2020.07.033
13. Waxenbaum, J. A., Reddy, V., & Varacallo, M. (2024). Anatomy, Autonomic Nervous System. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK539845/
14. Yap, J. Y. Y., Keatch, C., Lambert, E., Woods, W., Stoddart, P. R., & Kameneva,
15. T. (2020). Critical review of transcutaneous vagus nerve stimulation: Challenges for translation to clinical practice. Frontiers in Neuroscience, 14, 284–284. https://doi.org/10.3389/fnins.2020.00284

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