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The Ears as a Portal into the Nervous System
Music, Sound, Vagus and Vestibular Stimulation for Health and Healing
In my previous article,
I mentioned how the so-called Autonomic Nervous System, has been found to be not so automatic after all. That is, we can tap into it via various portals, such as the breath, and the eyes and vision, in order to consciously and actively change our Nervous System state.
Here, we will explore how the ears are another such portal, and how, through the ears, we can teach our Nervous System to be calm, become unstuck from defensive fight, flight or freeze states, and can bring balance back to the hemispheres of the brain, hence remedying the left brain hemisphere over-activation which is associated with defensive states, see:
Indeed, according to Dr Iain McGilchrist’s “Divided Brain” research, music is perhaps the most right brain hemisphere activating intervention there is.
Stimulation of The Middle Ear Muscles
The work of Dr Stephen Porges and co-workers on the connections of the muscles of the middle ear with the Autonomic Nervous System is most intriguing, profound, and important, as covered for example in “Audio-vocal interactions in the mammalian brain”, Handbook of Behavioral Neuroscience 19:393-402 , December 2010, by Stephen W. Porges and Gregory F. Lewis.
In particular, Dr Porges’s work covers how our "social engagement" system, responsible for calm and co-regulation, and conversely, our flight, fight, or freeze responses responsible for defensive Nervous System states, are affected by specific sounds. He explains how sounds and frequencies associated with calming human voices can change our internal states, and hence why specific sound therapies may be so healing in chronic conditions/trauma. Dr Porges’s work predicts the range and types of sounds which should work the best. This is another example how other people’s internal states can profoundly affect our own, see:
The basic premise of his work in this area, is that the muscles of the middle ear can act like a switch, changing the stiffness of the eardrum, which allows us to tune in better to different types (different frequency ranges) of sound, as we flip between calm, pro-social states, and threatened, defensive Nervous System states.
So when we are calm, relaxed, and socially engaged, the middle ear muscles configure the ear drum to be optimally and preferentially tuned into the frequencies and sounds of calm human voices. When our Nervous Systems perceive we are in danger, the switch gets flipped, and the middle ear muscles re-configures the ear drum to preferentially tune in to lower frequency sounds, often associated with predators and danger, and de-prioritizes the sound of calm human voices.
This hence explains why, when we are stuck in flight, flight or freeze defensive Nervous System states, we find it very hard to hear, listen to, or heed, what other humans are telling us, because our ears literally dampen the sound out. We also become very poor at reading the emotional content, or “prosody”, in other people’s voices, and the prosody or melodic quality of our own voice drops too.
Dr Porges’s profound insight was that this system could be reversed engineered. By feeding only the frequencies and melodies of the calm human voice into the ears, and damping out other sounds, this could trigger the middle ear muscles to switch back to the configuration of the calm state, and thus signal to the rest of the Nervous System that all is safe.
“This will recruit… the middle ear muscles, functionally calm the behavioral and physiological state by increasing Vagal [of the Vagus Nerve] regulation of the heart, and promote more spontaneous social engagement behaviors… triggering neural mechanisms that regulate the entire social engagement system with the resultant changes in [increased expression of the face] and autonomic state.”
Basically, we start to look and feel better when we listen to melodies.
Dr Porges also notes that the optimal frequency band for this purpose is the same as what mothers use to calm their infants by singing lullabies.
While humans can vocalize sounds outside of the optimal frequency band of calm voice, these types of sound are often associated with signals of danger and pain, such as shrill cries, or aggressive shouting, so those vocal frequencies which are higher and lower than the optimal are not conducive to a calm state.
“The generally accepted frequencies for human hearing are between 20 and 20,000 Hz, but the human frequency band of perceptual advantage is frequencies from approximately 500 Hz to about 4,000 Hz. Within these frequencies, concentrations of acoustic energies/resonances in the vocal tract in both male and female human speech occur. So this select frequency band, which conveys the information of human voice, is functionally amplified by the mechanisms of the middle ear muscles that dampen low-frequencies".
This is interesting, in that folks with Nervous System dysregulation tend to have quite pronounced auditory sensitivities, which can trigger fight, flight or freeze responses, but they tend to be most sensitive and most triggered by the high frequency and/or low frequencies outside of calming vocalizations.
Dr Porges points out that all this has profound implications for the design of medical centres, schools, prisons, etc. where such triggering sounds are currently ever present, including the low frequency hum of air conditioning, school bells, and beeping equipment in hospitals.
On the other hand, repeated listening to only the optimal frequencies of the calming human voice can be a form of neural exercise, strengthening the ability of the muscles of the middle ear to switch the ear drum’s configuration, increasing resilience to stress, and the ability to self-calm quickly after a stressful episode.
"The functioning and development of the muscles of the face and head involved in listening and in production of vocalizations parallel the maturation of the myelinated [ventral] Vagus Nerve. These become part of an integrated functional social engagement system, resulting in facilitating several adaptive behaviors including: an improved ability to regulate physiological state, to both self-sooth and maintain calm states, as well as to mobilize by withdrawing the vagal brake to explore, forage and defend.”
The Safe and Sound Protocol
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Dr Porges noted that hyper-sensitivity to high and low frequency sounds is particularly apparent in children on the autism spectrum, and that this could be caused by the atrophy of the middle ear muscle, such that they then find it hard to tune out these types of sound, and difficult to tune in to human voices. He hypothesised that by getting them to listen to the right types of sounds, i.e. those which mimic and emphasise human prosody of voice, this could strengthen their ability to flip the switch of the middle ear muscles, decrease their hypersensitive to sounds, and help them to engage in healthy pro-social activity.
In his article “Reducing Auditory Hypersensitivities in Autistic Spectrum Disorder: Preliminary Findings Evaluating the Listening Project Protocol”, Dr Porges developed a pragmatic interventional tool for delivering his idea.
"Auditory hypersensitivities are a common feature of autism spectrum disorder (ASD). In the present study, the effectiveness of a novel intervention, the listening project protocol (LPP), was evaluated in two trials conducted with children diagnosed with ASD. LPP was developed to reduce auditory hypersensitivities. LPP is based on a theoretical “neural exercise” model that uses computer altered acoustic stimulation to recruit the neural regulation of middle ear muscles.”
“LPP was hypothesized to reduce auditory hypersensitivities by increasing the neural tone to the middle ear muscles to functionally dampen competing sounds in frequencies lower than human speech. The trials demonstrated that LPP, when contrasted to control conditions, selectively reduced auditory hypersensitivities."
This LLP was later renamed “The Safe and Sound Protocol” (SSP), which is now available via online therapists. The SSP takes vocal music and songs, and emphasises and enhances the optimal frequencies of human vocal prosody contained with them, while damping lower frequencies, and these modified song tracks are then fed into the ears by headphones. The SSP has since found success not only for children with noise hyper-sensitivity, but also for adults with neurological issues, PTSD, chronic conditions and traumatic brain injury.
The SSP and the ideas behind it are just one example of how sound and music can be used as tools to improve wellbeing and enhance quality of life. Indeed, a few years ago, I stumbled across the brilliant myNoise website, which has a plethora of tuneable soundscapes to explore and enjoy. This is a fantastic free website which has an enormous range of sounds and music for relaxation, sleep, focus, motivation, brain training etc. that can be individualized and experimented with. Here, I will mention just a few examples, which I personally found interesting.
Brain Wave Entrainment
Under the “Brain Hacking” section of the myNoise homepage, you can find sounds designed to induce different frequencies of neural activity, and to put the brain into different states.
The Aural Scan is based on the work of French ENT specialist Dr Alfred Tomatis (1920-2001), who is also featured in the “Bridge of Sound” chapter of Dr Norman Doidge’s book “The Brain’s Way of Healing”. This feeds the brain the whole range of frequencies of the entire audible spectrum, providing a good stimulus to the brain's neurons, and retraining and resetting the muscles of the ear. Note, it is important to use the calibration function with this one, to tailor it precisely so that you are hearing all the frequencies as intended.
Music of the Human Voice
As Dr Porges’s theory rests on feeding mainly the frequencies of calming human voices into the ears, it may make sense that a capella and vocal music (rather than singing words) would be beneficial. The myNoise website includes several examples of this, which I found could have powerful effects on me. These include:
Lullabies for Adults
As mentioned by Dr Porges, the optimal frequency range for calming corresponds to the quality of the female voice mothers use to sing to babies. Hence seeking out and listening to songs which have the qualities of lullabies may also be helpful. Here are a couple of examples I found:
Clinical and Therapeutic Hypnotism
Another way the ears can be a portal into our Nervous System is via delivery of calming instructions to our conscious and subconscious brains, namely hypnotherapy. Many folks who suffer with chronic conditions or trauma may find forms of hypnotherapy very helpful.
I have personally found the BrainTap App very beneficial. It combines aspects of hypnotherapy, neurolinguistic programming, music and brainwave entraining sounds, including a special “double voice” hypnotherapy feature on some of the tracks. This has been instrumental in fixing my insomnia, and my brain loves listening to it.
My therapist, Lilian Sjoberg, uses a variety of techniques, including a form of Hypnotic Talk Therapy, which I have found enormously beneficial. We are thinking of recording some audios.
Caloric Vestibular Stimulation
Another way the ears have been found to be a portal into the Nervous System, albeit not sound or music based, is via the application of Caloric Vestibular Stimulation (CVS). CVS delivers a temperature differential, by making one of the ear canals cold, and the other warm, to provide neural stimulation. It has been found to be useful for relieve migraines, symptoms of Parkinson’s Disease, and other conditions.
According the wikipedia page, it can also induce a temporary remission of consequences of right hemispheric damage. It should also therefore be beneficial to chronic conditions, movement disorders, and traumas which involve the right brain hemisphere shutting down, or a right “cortical shock”, by re-activating the right hemisphere, and restoring balance. The Eye Guide MC device for Parkinson’s, which uses a weight on one ear, may work in a similar way.
Vagus Nerve Stimulation
Direct electrical stimulation of the Vagus Nerve has been found to be beneficial for conditions such as depression, epilepsy, POTS and many other Nervous System disorders. The type of Vagus Nerve Stimulation (VNS) provided by Healthcare systems usually involve surgical implantation of electrodes onto the Vagus Nerve as it runs down the neck. However, non-invasive and non-surgical types of VNS have been found to be just as successful, by clipping electrodes to the ear, especially the tragus. [Note, don’t try to rig this up at home, as you can fry your Nervous System].