Auditory agnosia, also known as pure auditory aphasia, is the inability to understand speech. People with this disorder lose the ability to understand language, repeat words, and write from dictation. Some patients with auditory agnosia describe hearing spoken language as meaningless sounds, as if the person is speaking a foreign language. However, the ability to speak spontaneously, read, and write remains intact. Patients also have a relatively better ability to process nonverbal auditory information, such as music, than to understand spoken language. People with pure auditory aphasia can also recognize nonverbal sounds. Patients retain the ability to interpret language by reading lips, hand gestures, and contextual cues. Sometimes, this agnosia is preceded by cortical deafness. Researchers have documented that in most patients with auditory agnosia, distinguishing between consonants is more difficult than distinguishing between vowels, but, like most neurological disorders, there is variability among patients. Auditory agnosia differs from auditory agnosia; Auditory agnosia has relatively intact speech comprehension systems despite their poor ability to recognize nonverbal sounds. Auditory agnosia is described as pure agnosia because it has a high degree of specificity. Despite the loss of speech comprehension, people with auditory agnosia typically retain the ability to hear and process nonverbal auditory information, speak, read, and write. This specificity suggests a disconnect between speech perception, nonverbal auditory processing, and central language processing. In support of this theory, there are cases in which speech and nonverbal processing disorders have responded differently to treatment. For example, some treatments have improved patients' written comprehension over time, while the same patients' ability to speak remained severely impaired. Auditory agnosia has been shown to be caused by tumors, especially in the posterior third ventricle, trauma, lesions, cerebral infarction, herpes zoster encephalitis, and Landau-Kleffner syndrome. The exact location of the damage that produces pure auditory aphasia is still debated, but it has involved the temporal plane, the posterior superior temporal gyrus, and white matter damage to the auditory nerve structures. Pure auditory agnosia is rarely diagnosed. Auditory agnosia can result from acute damage or from chronic progressive degeneration over time. Cases of severe head injury resulting in bilateral temporal lobe damage have been documented. In contrast, auditory agnosia has been shown to develop gradually over several years. In one such case, the patient showed progressive auditory aphasia over 9 years but no other evidence of cognitive decline. MRI showed cortical atrophy in the left superior temporal lobe region. In childhood, auditory agnosia can also be caused by Landau-Kleffner syndrome, also called acquired epileptic aphasia. Auditory agnosia is often the first symptom of this syndrome. A review of 45 cases suggested a relationship between prognosis and age of onset and found that patients with early onset had a poorer prognosis. In rare cases, auditory agnosia may be a symptom of neurodegenerative diseases, such as Alzheimer's disease. In such cases, auditory agnosia is usually followed by more severe neurological symptoms typical of Alzheimer's disease.