presented in written form. If both of these criteria are met and lack of auditory verbal comprehension is apparent, a diagnosis of AVA may follow. In at least one instance, the Boston Diagnostic Aphasia Examination has been used to profile AVA. This method was able to show that the patient experienced marked difficulty in speech perception with minor to no minor deficits in production, reading, and writing, fitting the profile of AVA. While this provides a well-known example, other verbal-audio test batteries can and have also been used to diagnose pure speech deafness. Cognitive deficits Auditory verbal agnosia is the inability to distinguish phonemes. In some patients with unilateral auditory verbal agnosia, there is evidence that the ability to acoustically process speech signals is affected at the prephonemic level, preventing the conversion of these signals into phonemes. There are two predominate hypotheses that address what happens within the language center of the brain in people that have AVA. One of the hypotheses is that an early stage of auditory analysis is impaired. The fact that AVA patients have the ability to read shows that both the semantic system and the speech output lexicon are intact. The second hypotheses suggests that there is either a complete or partial disconnection of the auditory input lexicon from the semantic system. This would suggest that entries in the lexicon can still be activated but they cannot go on to cause subsequent semantic activation. In relation to these two different hypotheses, researchers in one study differentiated between two different types of AVA. According to this study, one form of AVA is a deficit at the prephonemic level and is related to the inability to comprehend rapid changes in sound. This form of AVA is associated with bilateral temporal lobe lesions. Speech perception in patients with this form of AVA has been shown to improve significantly in understanding when the pace of speech is drastically slowed. The second type of AVA that the study discusses is a deficit in linguistic discrimination that does not adhere to a prephonemic pattern. This form is associated with left unilateral temporal lobe lesions and may even be considered a form of Wernicke's aphasia. Often individuals diagnosed with auditory verbal agnosia are also incapable of discriminating between non-verbal sounds as well as speech. The underlying problem seems to be temporal in that understanding speech requires the discrimination between specific sounds which