The temporal lobes are located slightly above the ears. They are involved in the reception and interpretation of auditory stimuli.
The primary auditory cortex is the site in the cortex where hearing registers. The primary auditory cortex in each temporal lobe receives sound inputs from both ears. Injury to one of these areas results in reduced hearing in both ears, and the destruction of both areas causes total deafness.
Adjacent to the primary auditory cortex in the left temporal lobe is Wernicke’s area. This is the languagearea involved comprehending the spoken word and in formulating coherent written and spoken language. It is usually in the left hemisphere.
When you listen to someone speak, the sound registers first in the primary auditory cortex. From there the sound is sent to the Wernicke’s area. This is where the sound is unscrambled into meaningful patterns of words.
The same areas that are active when you listen to someone speak are also active in deaf people when they watch a person using sign language. This area is also involved when you choose the words to use in speech and written expression.
Wernicke’s aphasia is a type of aphasia resulting from damage to Wernicke’s area. Although speech is fluent and words are clearly articulated, the actual message does not make sense to others. The content may be vague, or bizarre and may contain inappropriate words, parts of words, or gibberish of nonexistent words. People with this condition are not aware that there is anything wrong with their speech.
Another kind of aphasia is auditory aphasia, which is word deafness. It can occur if there is damage to the nerves connecting the primary auditory cortex with Wernicke’s area. The person is able to hear normally but may not understand spoken language, and perceive the sounds but have no idea what the speaker is saying. They hear it as a foreign language.
The remainder of the temporal lobes consist of the association areas that house memories and are involved in the interpretation of auditory stimuli.