Speech perception
Agnosia is "the loss or diminution of the ability to recognize familiar objects or stimuli usually as a result of brain damage". There are several different kinds of agnosia that affect every one of our senses, but the two most common related to speech are speech agnosia and phonagnosia.
Self-awareness
Anosognosia was a term coined by Joseph Babinski to describe the clinical condition in which an individual suffered from left hemiplegia following a right cerebral hemisphere stroke yet denied that there were any problems with their left arm or leg. This condition is known as anosognosia for hemiplegia (AHP). This condition has evolved throughout the years and is now used to describe people who lack subjective experience in both neurological and neuropsychological cases. A wide variety of disorders are associated with anosognosia. For example, patients who are blind from cortical lesions might in fact be unaware that they are blind and may state that they do not suffer from any visual disturbances. Individuals with aphasia and other cognitive disorders may also suffer from anosognosia as they are unaware of their deficiencies and when they make certain speech errors, they may not correct themselves due to their unawareness. Individuals who suffer from Alzheimer's disease lack awareness; this deficiency becomes more intense throughout their disease. A key issue with this disorder is that people who do have anosognosia and suffer from certain illnesses may not be aware of them, which ultimately leads them to put themselves in dangerous positions and/or environments. To this day there are still no available treatments for AHP, but it has been documented that temporary remission has been used following vestibular stimulation.