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Date of Graduation
Doctor of Philosophy (PhD)
Department of Communication Sciences and Disorders
Christopher G. Clinard
Spatial selective auditory attention plays a crucial role in listening in a mixture of competing speech sounds. Previous neuroimaging studies have reported alpha band neural activity modulated by auditory attention, along with the alpha lateralization corresponding to attentional focus. A greater cortical representation of the attended speech envelope compared to the ignored speech envelope was also found, a phenomenon known as 'neural speech tracking’. However, little is known about the neural activities when attentional focus is directed on speech sounds from behind the listener, even though understanding speech from behind is a common and essential aspect of daily life. The objectives of this study are to investigate the impact of four distinct target positions (left, right, front, and particularly, behind) on spatial selective auditory attention by concurrently assessing 1) spatial selective speech identification, 2) oscillatory alpha-band power, and 3) neural speech tracking. Fifteen young adults with normal hearing (NH) were enrolled in this study (M = 21.40, ages 18-29; 10 females). The selective speech identification task indicated that the target position presented at back was the most challenging condition, followed by the front condition, with the lateral condition being the least demanding. The normalized alpha power was modulated by target position and the power was significantly lateralized to either the left or right side, not the front and back. The parieto-occipital alpha power in front-back configuration was significantly lower than the results for left-right listening configuration and the normalized alpha power in the back condition was significantly higher than in the front condition. The speech tracking function of to-be-attended speech envelope was affected by the direction of ix target stream. The behavioral outcome (selective speech identification) was correlated with parieto-occipital alpha power and neural speech tracking correlation coefficient as neural correlates of auditory attention, but there was no significant correlation between alpha power and neural speech tracking. The results suggest that in addition to existing mechanism theories, it might be necessary to consider how our brain responds depending on the location of the sound in order to interpret the neural correlates and behavioral consequences in a meaningful way as well as a potential application of neural speech tracking in studies on spatial selective hearing.
Park, Heesung, "The directional effect of target position on spatial selective auditory attention" (2023). Dissertations, 2020-current. 105.