Dichotic Interaural Intensity Difference (DIID) Training in Patients With Neurological Lesions

Dichotic listening occurs when one attends to two different acoustical messages presented at the same time to both ears. This skill is important for understanding speech when in compromised listening situations, such as in the presence of background noise (Weihing & Atcherson, 2013). The corpus callosum and temporal lobes have been identified as playing an important role in dichotic listening, as patients with lesions to these regions score below normal limits on dichotic tests (Musiek, 1983). In addition to these patients with neurological lesions, dichotic listening deficits have also been identified in young children and older adults. For these latter two populations, it is suspected that these deficits are observed because of aging related changes to the corpus callosum (Musiek & Weihing, 2011). Dichotic listening deficits can be remediated by participating in auditory training (Musiek & Schochat, 1998). Auditory training consists of having the patient engage in auditory tasks that are administered over a CD player or computer. Auditory training which targets dichotic deficits is referred to as dichotic inter-aural intensity difference (DIID) training. The premise of this procedure is to have the patient perform dichotic listening tasks under less challenging listening conditions, and to gradually increase the difficulty as they improve. Research has shown that young children, older adults, and patients with neurological lesions tend to show improvements in dichotic listening following training (Musiek et al, 2008; Weihing et al, in preparation). In some cases, hearings in noise skills also improve post training. The mechanism for improvement in auditory processing that occurs as a result of DIID training is not known. It is suspected that benefits are received due to beneficial restructuring of the central auditory pathway and to improved attention skills (Weihing & Musiek, 2013). The present study would administer the training to 8 patients with neurological lesions and dichotic deficits. Brain imaging (functional magnetic imaging or f MRI) would be performed before the first training session and after the last session to help identify underlying neural mechanisms for DIID benefits. Dichotic interaural intensity difference (DIID) training in patients with neurological lesions) functional magnetic imaging (fMRI) which measures metabolic activity in the brain will be conducted before and after a 4 week, 12 sessions period of DIID auditory training on the participants with neurologically based CAPD and dichotic deficits. The training sessions will last about 20 -30 minutes each and planned for 3 sessions per week. During the imaging procedure the participants will be given a dichotic listening task to perform. A statistical as well as visual analysis will be used on the fMRI and behavioral findings to determine if there is a change in brain activity as a result of the auditory training. 1