8.3 Ear-brain Feedback System

Topic Progress:

How does the ear-brain feedback system work?

The ear and the brain feed information to each other via the nervous system. Sound Therapy positively benefits this system resulting in better ear and brain performance.

The ear and the brain are a feedback system where each communicates with the other in a loop.

Information is sent from the brain to the ears in the form of Motor stimuli (afferent nerves) – this is how the brain directs the muscles.

Information is also sent from the ears up to the brain in the form of Sensory stimuli (efferent nerves) –  this is how nerves inform the brain.

Tomatis drew on these physiological facts to create his theory that positive change induced by sound improves the ear-brain system, impacting on both brain function and ear function.

This process has been largely overlooked by conventional audiology practice. There has been very little research focus on the role of the middle ear muscles and their importance to our ear function and social engagement. Dr Tomatis was the first scientist to posit theories on their role.

Recently work by Stephen Porges and his development of Polyvagal theory has touched on the same systems and shown substantiation for what Tomatis observed decades earlier.

Observations of thousands of Sound Therapy listeners have clearly supported the theory that the middle ear muscles are actively engaged by the Sound Therapy process, and that when the muscles are activated we see improvements in such diverse conditions as blocked ear, Eustachian tube dysfunction, Meniere’s syndrome, hyperacusis  and auditory processing.

The ear and the brain form a feedback system

that can be enhanced by sound

The ear and the brain are a feedback system which is affected by sound

We know that sound can damage the ear. It is a less known fact that sound can also improve ear and brain function. When damage has occurred to the ear, gradually the brain loses its response to sound, through a process called auditory deprivation. When Sound Therapy is used, the opposite process occurs. Positive, stimulating sounds are presented to the ear. The result is greater responsiveness in the auditory centres in the brain, leading to greater social engagement. (Porges)

Motor stimuli

The Motor nerves, (called efferent, or descending nerves) – are the nerves which enable our muscles to be directed by the brain. Efferent nerves connect the brain to our middle ear muscles, and this allows the performance of our ear muscles to be modified by directives from the brain. (Richards)

Sensory stimuli

The Sensory nerves, (called afferent, or ascending) – nerves, inform the brain of experiences from our sensory organs. The sound vibrations received by the ear are carried to the brain by the sensory nerves. Positive change induced by sound improves the ear-brain system.

Sound Therapy and the feedback system

Sound Therapy impacts the ear-brain feedback system in three ways:

  1. improving ear muscle function
  2. simulating the receptivity and conductivity of the sensory cells (cilia) and auditory nerves
  3. remapping the auditory pathways in the brain. Thus, the whole ear brain feedback system is enhanced.