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Prosem Lecture: A Window into the Development of Real-time Binaural Processing through Eye Gaze
September 16, 2019 @ 12:00 pm - 1:00 pm
Presenter: Ellen Peng, Ph.D., Research Associate, Binaural Hearing and Speech Lab, Waisman Center, University of Wisconsin-Madison
Topic: A Window into the Development of Real-time Binaural Processing through Eye Gaze
To determine the location of a sound source, we use binaural cues – differences in arrival of time and level between the two ears. To measure whether human listeners are sensitive to binaural cues, the cue magnitude is varied and the just-noticeable-difference (JND) threshold is estimated. In children with normal hearing, binaural JND thresholds are similar to those of adults by 8 years of age; however, there is large individual variability (Ehlers et al., 2016). We hypothesized that maturation of binaural sensitivity is multifaceted: A prolonged processing time-course may be the cost for children to arrive at correct judgement of sensory inputs. To further understand the developmental trajectory of binaural processing, we recently developed a novel paradigm to record looking behaviors while children perform a binaural task. Eye gaze behaviors provided a window into the time course of decision-making when a child processed sensory input. During the binaural task, an eye-tracking camera recorded eye gaze position on the computer screen and data were analyzed to ascertain accuracy, speed and certainty. Children used a button press to report sound direction on the same trials. Results support our hypothesis. We found that children’s JND thresholds measured with button presses were similar to adults, i.e., mature by age 8-14 years. However, eye gaze data revealed a more protracted developmental trajectory; children in this age range were less decisive than adults, and prone to revise initial decisions even when their responses were correct. When cue magnitude was larger, children demonstrated greater certainty and faster processing of binaural cues.
[Work supported by NIH-NIDCD R01DC008365 to Ruth Litovsky and in part by NIH-NICHD U54HD090256 to the Waisman Center]