Schedule of Events | Symposia

Auditory masking release indexes human click-based echolocation performance

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Haydée G. García Lázaro¹ (haydee@ski.org), Santani Teng¹; ¹The Smith Kettlewell Eye Research Institute

Echolocation is an active sensing strategy enabling some blind individuals to detect, discriminate, and localize objects in their environment. Trained blind echolocators usually outperform novice blind and sighted individuals in echoacoustic tasks. Although visual experience and expertise often predict echolocation ability, the mechanisms underlying proficiency remain unclear. Previously, blind experts reliably localized virtual click-echo pairs, while sighted controls performed at chance. Because isolated echoes were easily localized by all subjects, the clicks may exert a forward masking effect that is attenuated by experience. To investigate this hypothesis both psychophysically and neurally, we systematically increased the echoacoustic SNR (echo-click amplitude ratio) for sighted controls (Experiment 1) and decreased it for blind experts (Experiment 2). In a 2AFC task, participants localized a spatialized virtual reflecting object 1-m distant at various azimuthal eccentricities across sequences of 2, 5, 8, or 11 click-echoes. Multivariate pattern analysis (MVPA) was applied to EEG responses to decode left vs. right stimulus position. Results showed that increasing echo SNR improved spatial localization parametrically in untrained participants, who reached near-expert performance (~76.6-95.5%). Expert echolocators maintained high accuracy (~92.8%) under unmodified acoustic conditions, with performance dropping to ~85.3% when the echo amplitude decreased by 33% and ~61.2% when decreased by half. Decoding timecourses across the first 2 clicks of each trial tracked spatial location and indexed performance across conditions in both experts and novices. These findings suggest that fine-tuned auditory masking release may underlie echolocation expertise and provide a framework to guide training and assistive technologies to enhance echolocation.

Topic Area: PERCEPTION & ACTION: Audition