Neural correlates of auditory attention

Abstract

This thesis investigates the neural mechanisms underpinning auditory attention in the context of sound localization, with a focus on processing spatial auditory information in complex acoustic environments. Utilizing frog calls as a novel stimulus—selected for their inherent ambiguity in localization—this study examines how the brain resolves directional cues under challenging conditions. A multimodal methodology was employed, integrating: (1) behavioral experiments assessing sound localization accuracy and reaction times, (2) electroencephalography (EEG) to measure the N2ac event-related potential (ERP) component linked to auditory attentional processes, and (3) mathematical modeling to uncover underlying computational principles. Results revealed that localization performance was significantly influenced by sound frequency and signal-to-noise ratio (SNR), with superior accuracy observed at lower frequencies (e.g., 700 Hz) and higher SNRs (e.g., 40 dB). Concurrently, EEG findings indicated that N2ac amplitude increased under conditions favoring attentional focus, reflecting enhanced neural engagement. Notably, in scenarios with degraded localization cues, participants exhibited a midline response bias, lending tentative support to the two-channel model of spatial hearing. These outcomes illuminate the dynamic interplay between sensory processing and attentional allocation in the auditory system, underscoring its adaptability to naturalistic auditory scenes. By leveraging frog calls as an innovative probe, this research provides fresh insights into the neural correlates of auditory attention and establishes a foundation for future investigations in auditory perception.