Sound Vibrations And The Vagus Nerve
The vagus nerve is the longest cranial nerve in the body. It originates in the brain and travels all the way down to the lower internal organs. It is a fundamental regulator of the parasympathetic nervous system, which controls all the body’s involuntary processes, such as digestion, heartbeat, respiration, and more. It is responsible for restoring relaxation after a response to stress or danger (which activates the sympathetic nervous system).
The strength of the vagus response is called “vagal tone”; it is determined by variations in heart rate that can be measured between inhalation and exhalation. During the inhalation, the heart speeds up, and during the exhalation, it slows down. The bigger the difference between these two phases, the higher the vagal tone. We need a high vagal tone in order to maintain a state of good health.
The Relevance of the Vagus Nerve
The ear and hearing have a substantial effect on the rest of the body because of their proximity to the vagus nerve.
The vagus nerve—the tenth cranial nerve—does not play an active part in hearing, so it is not normally considered in things that relate to music, hearing, and the like, outside of the medical field. However, this incredibly important nerve connects to the posterior wall of the external auditory canal, the lower part of the eardrum’s membrane, and in the middle ear, the stapedius (or stirrup muscle). From these parts of the ear, it makes its way all the way down to the lower internal organs, and is responsible for a high number of regulatory functions in pharynx, larynx, thorax and abdomen.
Basically, stimulating the ear means stimulating all the vital vegetative internal organs. This makes the ear a parasympathetic regulatory organ that uses innervation of the vagus nerve to affect the whole body.
The vibrations of sound tend to have a significant impact on all the areas of the body reached by this important nerve by resonating very close to it in the eardrums. In addition to that, most cranial nerves are either directly or indirectly connected to the ear.
This is one of the reasons why the use of sound therapy instruments, such as tuning forks and Tibetan singing bowls, can be so instantly calming, helping the body return to a nourishing state, the opposite of the fight-or-flight mode that stress triggers. Long and sustained sounds tend to be soothing and relaxing (evoking a parasympathetic response), whereas sharp and abrupt sounds tend to trigger alertness and alarm (a sympathetic response).
Auditory stimulation of the vagus nerve can also lead to reduced activity of the limbic system. The limbic system, located on both sides of the thalamus, includes the hypothalamus, the hippocampus, the amygdala, and other nearby areas. It is primarily responsible for our emotional life, and has a lot to do with the formation of memories.
A simple practice of toning (humming, or producing long vocal sounds, usually vowels) can have tangible calming effects by virtue of its auditory stimulation of the vagus nerve. This, in turn, causes limbic deactivation.
This is similar to certain therapies that employ electrical devices to stimulate the vagus nerve artificially. With your own voice, you can do the same in a completely organic way!
Listening to Life
The auditory system and its nerves become completely functional while we are still in the womb. The acoustic nerve is said to start to myelinate during the sixth month in utero, whereas the neocortex only completes myelination around adolescence. Myelin is an essential component of the nerve fibers. It is a coating substance that isolates the nerves and enhances the transmission of electrical signals.
Also, the area in the temporal lobe of the brain where sound signals are received is functional before birth, and the inner ear reaches its full adult size. That makes sense because while we are still in utero, we cannot rely on our sense of sight, but we can start receiving vitalizing signals from the environment via the ideal medium of water, in which sound travels very effectively.
Other important nerves to consider when working with sound in a therapeutic way are:
The trigeminal nerve (fifth cranial), which branches out to the muscles in the middle ear, impacting the eyes, nose, sinus, jaw, teeth, lips, cheeks, hard palate, and tongue. It is responsible for sensations in the head.
The facial nerve (seventh cranial), which connects to the ear canal and is responsible for facial expression and the opening of the mouth.
The glossopharyngeal nerve (ninth cranial), which connects to the eustachian tube and the tympanic cavity. It’s also responsible for sensations in the pharynx, soft palate, tongue, and tonsils, and controls the reflexes of respiration, blood pressure, and heart rate.
Given the importance of all these nerves, one thing is certain: Our brain really is wired for sound!