Jae Hee Lee1,, Mallory Orr1, Hwan Shim1, Inyong Choi1
1Communication Sciences & Disorders, University of Iowa, Iowa, United States of America
Auditory selective attention is a crucial mechanism for understanding speech in everyday environments. Top-down selective attention allows expectations to enhance the neural representation of sounds collected by the auditory sensory system. As most cochlear implant (CI) users struggle to recognize speech in noise, it is imperative to understand if CI users exhibit auditory selective attention activities that involve modulation of neural responses to target speech and if such attentional ability predicts their speech-in-noise performance. Our experiment is designed to assess the strength of attentional modulation within the human auditory pathway. Both participants with normal hearing (NH) and with CI were given a pre-stimulus visual cue that directed their attention to either of two sequences in stationary background noise and asked to select a deviant syllable in the target stream. Due to the misaligned timings of the syllables in each stream, we are able to examine the event-related potential (ERP), a proxy for attention modulation, in response to each syllable provided in the stream. We hypothesized that the amplitude of ERPs would be greater when the syllable is attended if either group is capable of employing auditory selective attention and that the difference of ERP amplitude between attended and unattended trials predicts the performance in a speech-in-noise task. Our analysis showed that the amplitude of ERPs for the attended syllable was greater than that for the unattended syllable with the CI subjects, exhibiting that attention modulates CI users’ cortical responses to sounds. Moreover, the strength of attentional modulation showed a significant correlation with the same CI users’ speech-in-noise performance. The difference between ERP amplitudes for attended and unattended syllables existed but was weaker for NH subjects. These results show that the attentional modulation of cortical auditory evoked responses provides a valuable neural marker for predicting CI users’ success in real-world communications.