Two ears: two cerebral hemispheres

May 28, 2012 by France Morrissette
The brain acts as headquarters for the central nervous system, controlling our ideas and thoughts. It is home to over a hundred billion interconnected nerve cells that transmit and receive messages from different parts of the body. These cells are the seat of intellectual, sensory and motor functions.

The brain is divided into two hemispheres, and as a general rule, these are organized in the following way:

hémisphère, lobe.jpgThe left hemisphere: The brain’s left hemisphere is the rational side, the primary centre for language, computation and analysis.

The right hemisphere: The right hemisphere excels in everything visual and spatial, perception and intuition. The right hemisphere of the brain is associated with creativity and music.



hémisphère, lobe.jpgEach hemisphere is subdivided by fissures forming several lobes: the limbic lobe, the insula, the frontal lobe, the parietal lobe, the occipital lobe and the temporal lobe containing the taste, memory and hearing centres. The auditory cortex is responsible for analyzing the information we receive through hearing.

Each cerebral hemisphere processes information according to its speciality, and then forwards its results to the other half of the brain. For example, to stretch the right leg, the left hemisphere is what triggers the movement.

Binaural hearing

Nature has equipped us with two ears and two cerebral hemispheres. Each cerebral hemisphere analyzes the messages transmitted by both ears, which means it is important that each ear is functioning well.

Studies show that hearing-impaired people with bilateral hearing aids describe sounds as having more clarity, intensity, proximity and softness, and report an improvement in their ability to understand conversation in noisy environments. In short, binaural hearing provides a better hearing experience than monaural hearing.

Not only do our two ears allow us to hear, they also let us locate sounds in our environment. For example, your ears don’t just let you know a car is coming, they also tell you the direction from which it is arriving. With his eyes closed, a person with bilateral hearing aids (both ears corrected) is able to tell if a vehicle is arriving from the left or the right. In addition, hearing aids stimulate the reorganization mechanisms of the auditory cortex (brain plasticity) and improve cognitive and social performance.*

Hearing aids “re-educate” hearing, even in the very elderly. So it is never too late to reap the benefits of modern digital technology!

To learn more, do not hesitate to consult an audioprosthetist at any Lobe Santé auditive et communication multidisciplinary clinic.


* See the article “La privation sensorielle,” Lobe Magazine, Vol. 7, No. 1, p. 8.

– Mariebs, Elaine N. Principes d’anatomie et de physiologie humaines, Éditions du renouveau pédagogique.

– Tortora, Gerard J., and Sandra Reynolds Grabowski. Principes d’anatomie et de physiologie.

– Purves, Dale (2003). Neurosciences, 2nd edition, trans. J. M. Coquery (De Boeck).

– Revue Audio info (April 2004).