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The Science of the SSP

The Safe and Sound Protocol (SSP) was designed by Dr. Stephen Porges based on decades of research that is now known as the Polyvagal Theory. To understand the science of the SSP, it can help to first understand our own body and the nervous system.

The Autonomic Nervous System

Our involuntary bodily functions, such as breathing, heart rate, and digestion, are regulated by a network of nerves called the autonomic nervous system, which has two parts: the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System

You can think of the sympathetic nervous system as a mobilization system that would support our "fight-or-flight" responses. It functions like a gas pedal, mobilizing internal resources in response to danger. When this happens, you might feel an increase in your heart rate, fast and shallow breathing, tension in your neck and shoulders, and anxiousness.

Parasympathetic Nervous System

The parasympathetic nervous system is classically call the "rest-and-digest" state, which helps us heal, recover and conserve energy when we feel safe.

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Through Dr. Porges' Polyvagal Theory, we now understand that the vagus — the primary component of the parasympathetic nervous system — has two structural pathways with different functions. 

When we feel threatened, with no way to run or fight, one branch of this system will shut us down. In this state, you might notice extreme fatigue, difficulty with digestion and feelings of depression. This is our body doing its best to preserve our resources to keep us alive.

​In turn, when we feel safe, another branch of the parasympathetic system supports our ability to connect socially with others and to have balanced, efficient and healthy bodily systems. In what Polyvagal Theory calls the Social Engagement State, this is when we feel calm, connected and more resilient to life's challenges.

Your autonomic nervous system is always asking the question"Am I safe?" 


But what if it's tuned to detect threat and unable to detect cues of safety?

The Physiological Loop of Defense

According to Polyvagal Theory, the autonomic nervous system is the foundation of our well-being. But when it becomes stuck in a state of chronic defense, we become unable to restore our nervous system to a place of safety.

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In a state of chronic defense, the autonomic nervous system is biased to detect and interpret cues as dangerous

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Detecting cues as dangerous, even when intentions are positive or neutral, limits ability to connect, leading to a greater state of defense

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Feedback Loop

of Defense

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This bias leads to a Social Engagement System becoming dormant, perpetuating the biased detection of cues as dangerous

When this happens, our auditory processing system becomes trained to detect acoustic cues of danger (i.e., low-frequency sounds of a potential predator approaching) in the background instead of the human voice, and we then become unable to engage with the social world around us.

The Safe and Sound Protocol interrupts and redirects this feedback loop with cues of safety.

How It Works

The SSP is designed to reduce sound sensitivities, and improve auditory processing, behavioral state regulation and social engagement behaviors.

Delivered over five hours of filtered music through over-the-ear headphones, the SSP trains the auditory processing system to tune into cues of safety signaled by the frequencies of the human voice, which stimulates the social engagement system through the neural network associated with listening.


Want to learn more? Download our informational brochure and share with your existing provider to see if the SSP may be an option for you:


Frequently Asked Questions

What does the music sound like?

The SSP uses music that you may already be familiar with. The music is put through an algorithm that enhances intonation changes within the frequency range of the human voice, training the auditory processing system to attune to cues of safety. You may not even realize that the music has been altered!

Can I do the SSP by myself without a provider?

The SSP is a powerful therapeutic intervention and is not available for use without the supervision of a trained professional (e.g. therapist, licensed social worker, mental health practitioner, clinician, etc.). All SSP providers are required to complete an extensive training and certification course prior to delivering the SSP to ensure safe and effective delivery.

What does a listening session look like?

Listening sessions can vary between providers depending on intake assessments, and usually can include a combination of client education, regulating activities and listening to the SSP. We recommend speaking with your existing provider about SSP delivery.

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