Browsing by Subject "Auditory selective attention"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Behavioral and Neural Correlates of Auditory Selective Attention
    (2022-04) Lu, Hao
    The human auditory system organizes incoming sounds into auditory streams, allowing us to selectively focus on one stream of interest against a background noise from other sources. While selectively attending to an auditory stream, listeners can exhibit behavior and neural responses correlated with their intent. This dissertation investigates both behavioral and neural correlates of auditory attention. In natural group conversation settings, we found that the listener’s head was generally oriented towards the target talker with a fixed undershoot, while their eye gaze accurately marked the location of the target talker. The relationship between attention to target talker and head and eye moments was unaffected by age, hearing loss or background noise level. The results have potential implications for future hearing aids with sound source selection basing on head and eye movements to improve signal-to-noise ratio (SNR) and speech intelligibility. Neural correlates of selective attention were examined at the level of responses to individual components within sequences of complex tones. These responses were elicited either via a probe tone that followed the end of a sequence of competing complex tones, or via the auditory steady-state response (ASSR) elicited during the ongoing tone sequences. Before analyzing the attentional effects, we conducted a systematic evaluation of pre-processing and quantification methods for envelope following responses (EFRs), including the ASSR. The most efficient method was also one of the simplest: the root-mean-square of the all-channel phase locking values (PLVs). Based on these findings, we tested the hypothesis, derived from the temporal coherence theory, that neural responses to individual frequency components within an attended stream should be enhanced by virtue of being temporally coherent with the object of auditory attention. In fact, neither the probe-tone nor the ASSR measure showed significant attentional modulation. The results suggest a form of hierarchical processing, whereby neural enhancement occurs at the level of objects, rather than individual components.