The Brain’s Role
Much of the brain cortex is involved in hearing. This is due in part to the complexity of language and the necessity for the brain to make all the connections necessary for this most complex of human feats. In one sense, over two thirds of the cerebral cortex is involved in hearing and language. However, the primary auditory cortex – that cortical area where the first neural information reaches the conscious centers – is located on the temporal lobe. An area about the size of a quarter dollar appears to be the “organizational area” which receives the neural chemical input from the cochlea and sends notification of this information to almost all of that half of the cerebral cortex-association areas. Also, the hearing from one ear goes to both sides of the brain; the cortex on the opposite side from the ear receives approximately 75% of the information while the same side receives about 25% of the information.
Damage and Disease
When damage to hearing takes place because of interruption or lack of cortical function, this is typically associated with other diseases or injuries – e.g., strokes, aphasia, trauma, or systemic problems. There are types of developmental problems, such as those associated with Attention Deficit Disorder (hyperactivity) that may be auditory in nature. And there are likely developmental deficits that are associated with other “global” brain problems that affect hearing.
The function of the auditory cortex is to “hear.” That is, the appreciation of all sensory input occurs in the cortex of the brain. So it is with audition. We interpret, associate, and generally translate all energy from the ears and hearing nerves in the cortex.
These hearing problems are not typically mitigated or repaired with medicines or surgeries offered by ear specialists. However, there is considerable hope for the future management of these sorts of deficits. We are just beginning to understand what causes these problems – and understanding leads to remedies.