From signal to symbol: Where is the auditory processing deficit?
Target Investigator:
Kyoko Nagao, PhD
Research Scientist
Mentors: Thierry Morlet, Ph.D.
Arild Hestvik, Ph.D.

The goal of this project is to specify the neurophysiologic processes contributing to auditory impairment in children with Auditory Processing Disorder (APD). Children with APD exhibit normal hearing based on audiometric tests, but have difficulty understanding speech in noisy environment. Despite the fact that such population exists, the underlying impairments resulting in APD are not fully understood. A common theory is that these deficits result from impairments in the processing of information in the auditory modality at either the central and/or the peripheral auditory system. Previous studies suggest that the APD involves auditory impairment at a low sensory level, yet we do not know whether APD is an impairment in the early stage of sound processing, or an impairment in mapping acoustic signals to abstract language-specific speech sound representations (phonemes). There are two specific aims of this research project. The first aim is to identify impaired neurophysiological processes contributing to poor speech perception in children with APD using a varying standards mismatch negativity (MMN) paradigm. The second aim is to characterize the relationship between clinical assessment of speech perception ability and phonemic MMN responses in children with APD. Our long term goal is to develop a new EEG based biomarker for assessing whether a child’s speech perception problem is caused by impaired phonetic processing, or impaired access to phonemes.