Autistic individuals typically have problems processing auditory information. One acoustic processing problem occurs when a person hears speech sounds but does not perceive the sounds' meaning. For example, if someone says the word 'shoe,' the person may listen to the speech sound, but they do not understand its meaning. Sometimes, others interpret the lack of speech comprehension as an unwillingness to comply. However, the person may not retrieve the meaning of the sound at that particular time.
             Eric Courchesne of the University of California at San Diego has found significant impairments in auditory processing in autistic individuals using P300 brain wave technology (see Courchesne, 1987 for a review). The P300 brain wave occurs 300 milli-seconds after the presentation of a stimulus. (The 'P' refers to the positive polarity of the brain wave.) The P300 is associated with cognitive processing, and this brain wave is considered an indication of long-term memory retrieval (Donchin, Ritter, & McCallum, 1978). Edelson et al. (1999) examined auditory P300 activity before and three months following auditory integration training (AIT). Three autistic individuals participated in the experimental AIT group, and two autistic individuals participated in a placebo group. All five individuals had abnormal auditory P300 activity before AIT, indicating an acoustic processing problem. Three months following AIT, the results showed dramatic improvement in P300 activity for those who received AIT (i.e., normalization of P300 activity) and found no change in those who received the placebo.
             We do not know the underlying reason for auditory processing problems in autism; however, autopsy research by Drs. Bauman and Kemper have shown that an area in the limbic system, the hippocampus, is neurologically immature in autistic individuals (Bauman & Kemper, 1994). The hippocampus is responsible for sensory input as well as learning and memory. ...