Difficulty listening to one person speak in the presence of many other competing sounds is a significant problem for many people, even some with normal hearing test results. Understanding speech in these adverse conditions improves markedly when sound sources are spatially separated, an effect known as spatial release from masking. If a person looks toward a talker of interest, seeing that person's face provides visual spatial and temporal information that can improve understanding even more, making this a common and important audiologic rehabilitative strategy. However, recent work performed by the candidate hints at a perceptual benefit from the mere act of directing gaze toward that sound. Furthermore, despite wide acceptance of the importance of spatial hearing and visual information to auditory selective attention, the interplay between these processes is largely unexplored and little work has been done to characterize how differences in spatial hearing abilities among individual listeners affects their ability to listen in noisy situations. In the mentored training phase of this research program, the candidate will perform two experiments exploring the impact of eye gaze and visual information while receiving training in visual neuroscience. He will first build on his previous findings by measuring the effects of directed eye gaze on spatial release from masking in a multiple- talker speech task (Aim 1). Next he will assess the low-level benefits of spatial and temporal visual information to selective attention in task that uses stimuli that exhibit some of the basic characteristics of speech but are non-linguistic in nature (Aim 2). After progressing to the independent phase of the award, the candidate will examine the range of auditory spatial abilities in normal hearing listeners and the effects of binaural deficits on listening performance in multiple-talker environments, then whether deficits can be ascertained electrophysio- logically, and ultimately if spatial deficits change the way listeners leverage visual cues (Aim 3). This research is clinically relevant because it will provide important insights into listening in noise: how spatial hearing deficits affect understanding in the individual, and what specific visual factors underlie important audio-visual coping strategies. The work will facilitate the candidate's immediate career goals of becoming an audio-visual researcher with the necessary substantial experience in both sensory modalities and the ability to execute experiments using measures of both behavior and brain activity. Training during the mentored phase will be supplemented by formal coursework in the physiology and neuroscience of the visual system, meetings with the co-mentor's visual neuroscience group to learn the current literature and critically evaluate the candidate's own work, and by learning nonscientific skills such as mentoring and lab management from the primary mentor as well as institution-wide seminars. The research performed and training provided during this award will be critical for the candidate's long-term goal of directing a lab whose research yields important new insights into how people understand and navigate their sensory world.
Combining information from both ears is important to our ability to listen to one person speaking in a noisy environment-but it's something that many people, even with normal hearing tests, struggle with. In this program we will investigate two aspects of this issue: (1) how the visual system can improve what we hear and allow better listening, and (2) whether problems perceiving the differing locations of competing sound sources can lead to these difficulties.
| Bizley, Jennifer K; Maddox, Ross K; Lee, Adrian K C (2016) Defining Auditory-Visual Objects: Behavioral Tests and Physiological Mechanisms. Trends Neurosci 39:74-85 |
