Sensory processing difficulties have been well documented in children with Autism Spectrum Disorder (ASD). In fact, "hyper- or hypo-reactivity to sensory input" has recently been added to the diagnostic criteria of this disorder. Hyper-reactivity features are particularly disruptive to children's abilities to engage in everyday activities and pose a significant problem for patients and their families. In children with high functioning pervasive developmental disorder, hyper-sensitivity is associated with symptoms of anxiety and depression. For sensory processing difficulties, children with ASD are primarily referred to Occupational Therapy (OT) services for treatment. These patients are also often seen by mental health professionals to address related disorders such as anxiety, ADHD and behavior problems. Currently, there are no evidence based approaches for specifically addressing auditory hyper-reactivity in ASD. Exposure and response prevention (E/RP), derived from systematic desensitization, is highly effective at reducing avoidance behaviors associated with phobias and obsessive and compulsive disorder (OCD). In mental healthcare settings, ER/P has been shown to be effective for reducing compulsive behaviors in children with OCD and concurrent ASD. E/RP has also been piloted for treating restricted, repetitive behaviors in ASD and demonstrates good feasibility. E/RP may also be useful for reducing aversive responses to auditory stimuli in children with ASD. Occupational Therapists (OT) are the primary service for providing treatment for sensory processing and arousal level modulation difficulties in children with ASD. Thus, OTs are potentially well suited to provide an E/RP aimed at reducing sensory hyper-reactivity in ASD. This study will investigate the feasibility and efficacy of utilizing an E/RP approach for treating auditory hyper-reactivity in ASD.