How do we attend dynamically in time during listening?

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Speech is often difficult to understand, either due to situational demands (e.g., background speech in a crowded bar), or due to age-related changes in sensory systems that result in degraded speech encoding. My research program aims to improve our knowledge of the fundamental mechanisms of how auditory sensory encoding and cognitive processing interact to shape listening experiences and speech comprehension, and how age-related changes in neural circuits lead to adverse listening experiences. The long-term goal of this program is to deliver the mechanistic foundations that ultimately can help people with hearing difficulties to comprehend degraded speech better and to enable them to stay engaged in communication. The research that I propose for this NSERC DG considers two key factors that are crucial for speech comprehension in real life but have thus far received little attention: situational demands vary over time (e.g., changes in the intensity of background speech) and not all words are relevant for a listener to follow a conversation. Listeners can thus attend specifically at times when listening is expected to be difficult and when relevant information is expected to occur in order to avoid fatigue. Control over the timing and magnitude of attention makes listening temporally dynamic. Older adulthood is associated with reduced cognitive control, but little is known about how this affects the ability to recruit attention dynamically to points in time when relevant information in acoustic environments is expected to occur. This work will deliver a detailed account of how listeners attend dynamically over time during listening. The proposed research has four specific aims: (1) to examine how well individuals can recruit attention dynamically during listening; (2) to investigate how speech-relevant information (e.g., temporal regularity, syntactic structure) affect dynamic attention in time during listening; (3) to identify the key brain regions and networks that support dynamic attention; and (4) to explore how the ability to control attention dynamically during listening changes with age. We will utilize an integrative approach that combines behavioral, eye (pupillometry & microsaccades), and neural (electro-/magnetoencephalography) measures to comprehensively characterize people's ability to attend dynamically in time during listening, the underlying mechanisms, and the effects aging may have. Understanding the fundamental processes that underlie dynamic control over attention will help gain better knowledge of the factors contributing to adverse listening experiences. Our work will demonstrate how/when people engage in their listening environments, and when they decide to stop listening. This will be important for creating guidelines for the design of public spaces that are inclusive of all abilities. Our research will further contribute to physiology-based technology (e.g., gaming) that relies on a user's dynamic regulation of attention.