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The primary auditory cortex is one of three parts that make up the auditory cortex. It is located between the secondary and tertiary auditory cortexes, in the temporal lobe of the brain. This part of the cortex has the responsibility of processing sound information for the brain.
All sensory information has to be processed by a cortical area of the brain in order to be perceived. Sound information is processed by the primary auditory cortex. The details of sound, such as frequency, location, and volume, are all processed by this particular section of the auditory cortex. It has the ability to react to different frequencies.
The primary cortex is divided by neurons. Each of these neurons are grouped together according to the specific sound frequencies they respond to. Neuronal encoding of sound is the process by which the neurons distinguish sound. Within the primary auditory cortex, each area responds to different frequencies. For instance, the front area is more responsive to higher frequencies while the back area responds better to lower frequencies.
Damage to the primary auditory cortex can cause many problems. When the entire primary area is damaged, a person is not aware of the sounds that are heard, but this person still has the ability to act in reflex to any sounds. With this problem, for example, a person might flinch at a loud noise but be unable to tell anyone what noise was heard or why the startled reaction occurred. This damage prevents the primary area from processing auditory information into perception.
Partial damage of the primary auditory cortex is not nearly as severe as whole damage but causes some hearing problems as well. When only one section of the primary area is damaged, certain frequencies are not perceived. For example, if one section that processes low frequency sound is damaged, the brain does not perceive any sounds that would be processed by that section. Middle level and high frequencies are unaffected. Similar to whole damage, the sound is heard but not processed completely.
There are several noise health effects that can result in damage to the primary auditory cortex. Birth defects cause damage found in newborn babies. Some diseases, such as meningitis and chickenpox, can lead to auditory cortex damage and hearing loss. Most commonly, however, consistent exposure to loud noise leads to damage. In some instances, the damage is temporary but in many cases damage can be permanent.