When we hear, sound waves travel from the outer ear, through the middle ear into the inner ear where the vibrations stimulate thousands of tiny hair cells. The tiny hair cells in our inner ear send electrical signals to the auditory nerve which is connected to the auditory centre of the brain where the electrical impulses are perceived by the brain as sound. The brain translates the impulses into sounds that we know and understand.
Our brain is a filter
Our brain is also active when we discriminate relevant sounds from background noise. Our brain can filter out unwanted noise so that we can focus on what we are listening to. And researchers have found that the brain activity is greater in the left half of the brain when we discriminate sounds from noise. In other words, the cocktail party effect occurs in the left side of our brain.
In the same way, our brain turns up the volume when we speak. When it comes to our own speech, there is a network of volume settings in the brain which can amplify the sounds we make.
Tinnitus in the brain
Our brain may also play an important role when it comes to tinnitus.
A research team has been able to eliminate tinnitus in a group of rats by stimulating a nerve in the neck and playing a variety of sound tones over a period of time. The therapy, which is similar to pressing a reset button in the brain, was found to help retrain the part of the brain that interprets sound so that errant neurons reverted back to their original state and the ringing disappeared.
Another research team found that tinnitus is generated not by the ear, but by neurons firing in the brain.
“Tinnitus is not generated by processes in the ear, but by changes in the brain when hearing loss occurs,” one of the researchers said.