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201161 https://hdl.handle.net/2286/R.2.N.201161 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2025 40 pages Masters Thesis Academic theses en Xue, Yihan Zhou, Yi YZ Luo, Xin XL Daliri, Ayoub AD Arizona State University Partial requirement for: M.S., Arizona State University, 2025 Field of study: Speech and Hearing Science The Precedence Effect (PE) refers to the phenomenon in which the first-arriving sound dominates auditory spatial perception, suppressing subsequent reflections. Echo suppression, a key aspect of the PE, enables accurate sound localization in reverberant environments by prioritizing directional cues from leading sounds over lagging echoes. While visual cues are known to influence auditory spatial perception—such as in the ventriloquism effect, where sound is mislocalized toward a visual stimulus—it remains unclear how vision affects the processing of multiple auditory events like echoes. Most audiovisual research focuses on single-source localization, leaving a gap in understanding how visual stimuli influence echo suppression in complex acoustic environments.To address this, the present study investigated how visual stimuli affect echo suppression and auditory localization using simulated echoes in a stereophonic setup. Two conditions were compared: audio-only (AO) and audiovisual (AV). In the AO condition, participants heard broadband noise bursts with varying echo delays (0–14 ms). In the AV condition, a brief light stimulus (LED) was presented synchronously with the sound, randomly located at either the leading sound position (AVlead) or the lagging sound position (AVlag). Six participants with normal hearing completed two tasks: (1) reporting echo perception via button presses and (2) localizing the leading sound using eye movements. Eye-tracking and Arduino devices were integrated through MATLAB to register behavioral responses. Echo perception increased with longer delays, consistent with PE principles. However, echo thresholds did not significantly differ between AO, AVlead, and AVlag conditions, suggesting visual cues did not alter the auditory system’s ability to suppress echoes. In contrast, visual effects emerged in localization behavior. When visual cues were aligned with the leading sound (AVlead), participants showed enhanced localization accuracy. In contrast, cues aligned with the lagging sound (AVlag) introduced variability and bias toward the visual cue, reflecting visual capture. These effects were more prominent at longer delays and varied across individuals. These findings highlight the complex role of vision in auditory spatial processing. They offer insights for multisensory integration models and inform applications in hearing aids, auditory training, and virtual reality systems, where accurate spatial perception is essential. Audiology Cognitive Psychology Experimental psychology Audiovisual Perception Echo Suppression Multisensory Integration Precedence Effect Sound Localization Visual Capture Effects of Visual Stimulation on Echo Suppression