Institution: Smith-Kettlewell Eye Research Institute
Poster Title: Optimizing signal parameters to enhance echoacoustic perception of objects in humans
Abstract: Echolocation, a strategy used by animals like bats and dolphins, is also employed by a growing number of blind and visually impaired (BVI) individuals, who use tongue clicks and listen to the resulting echoes to create mental representations of their surroundings. Despite its potential, the mechanisms underlying human echoacoustic perception are not well understood, limiting its broader application in the BVI community. To address this, our lab has developed "Robin," a wearable ultrasonic echolocation device that emits user-initiated ultrasonic signals, records the resulting echoes, and processes them into human-audible frequencies for playback. Robin interfaces with a web app that offers a wide range of customizable parameters, allowing users to tailor signals to their personal needs while providing researchers with a large, customizable parameter space for investigating the perceptual mechanisms of human echolocation. To assess the efficacy of this platform, we tested the perceptual discriminability of Robin-processed echoes from common furniture items. Preliminary results from sighted participants (no echolocation expertise) on a 2-AFC match-to-sample task showed above-chance performance in discriminating Robin-processed echoes reflected by four different objects (tested against every other object). These results indicate that the artificially processed echoacoustic signals produced by Robin encode perceptually relevant information that enables non-experts to successfully distinguish between different objects, based solely on their reflected echoes. Furthermore, visualizing the perceptual and stimulus spaces for this task using MDS revealed that perceptual discriminability reflected acoustic dissimilarity in the echo signatures of different objects, suggesting that observers were able to integrate increasing acoustic differences along multiple dimensions to improve performance. Ongoing work aims to leverage Robins customizable signal parameter space to identify specific acoustic cues best suited to different tasks and environmental features, paving the way for designing future echolocation-based aids for BVI individuals.