Development of binaural hearing in humans: Behavioral and physiological factors

Auditory sound localization and separation of sources in noisy environments depend on the integrity of binaural processes. Throughout development, binaural hearing undergoes changes that can be captured with behavioral and physiological assays. Although it may be somewhat easier to capture binaural abilities, and their development, by employing measures of sensitivity, i.e., just noticeable difference (JND) thresholds, perception cannot be fully understood by relying on threshold estimates. Rather, binaural development can be more fully understood by capturing features of decision-making such as time to decision, certainty with which the listener arrives at a decision and task-related attentional resources that are harnessed depending on the salience of the auditory stimulus. We probe binaural perceptual phenomena through a combination of psychophysics, pupillometry, eye tracking, and electroencephalography (EEG), showing that beyond the JND, critical information about perception is captured through a multi-dimensional approach. We investigate binaural development in individuals with typical hearing and in cochlear-implant users, the latter being vulnerable to disruption of establishment of binaural circuits. Our studies test hypotheses regarding limitations during development placed by CI signal processors, which discard temporal fine structure (TFS) of sounds and encode acoustic information by the envelope modulations (ENV).