Abstract
Sighted people predominantly use vision to navigate spaces, and sight loss has negative consequences for independent navigation and mobility. The recent proliferation of devices that can extract 3D spatial information from visual scenes opens up the possibility of using such mobility-relevant information to assist blind and visually impaired people by presenting this information through modalities other than vision. In this work, we present two new methods for encoding visual scenes using spatial audio: simulated echolocation and distance-dependent hum volume modulation. We implemented both methods in a virtual reality (VR) environment and tested them using a 3D motion-tracking device. This allowed participants to physically walk through virtual mobility scenarios, generating data on real locomotion behaviour. Blindfolded sighted participants completed two tasks: maze navigation and obstacle avoidance. Results were measured against a visual baseline in which participants performed the same two tasks without blindfolds. Task completion time, speed and number of collisions were used as indicators of successful navigation, with additional metrics exploring detailed dynamics of performance. In both tasks, participants were able to navigate using only audio information after minimal instruction. While participants were 65% slower using audio compared to the visual baseline, they reduced their audio navigation time by an average 21% over just 6 trials. Hum volume modulation proved over 20% faster than simulated echolocation in both mobility scenarios, and participants also showed the greatest improvement with this sonification method. Nevertheless, we do speculate that simulated echolocation remains worth exploring as it provides more spatial detail and could therefore be more useful in more complex environments. The fact that participants were intuitively able to successfully navigate space with two new visual-to-audio mappings for conveying spatial information motivates the further exploration of these and other mappings with the goal of assisting blind and visually impaired individuals with independent mobility.
Highlights
More than 250 million people are visually impaired, with over 35 million of this group classified as blind [1, 2]
The current study has explored the feasibility of two novel visual-to-audio mappings for the task of spatial navigation: simulated echolocation and distance-dependent volume modulation of hums
The device created an immersive virtual world in which participants were able to physically walk around virtual scenes. This is the first work to make use of such an experimental paradigm for the task of spatial navigation, and we believe this approach will be of interest to others working in the dynamics of mobility and spatial navigation
Summary
More than 250 million people are visually impaired, with over 35 million of this group classified as blind [1, 2]. While certain causes of visual impairment can be prevented or treated, a large proportion of sight loss remains without a cure [3]. New treatment approaches such as retinal prosthetics, optogenetics, and gene therapy offer hope for the future, but at present are at a research or early implementation stage and await evidence of real-life benefit to patients [4]. While blind or visually impaired individuals are often able to learn to successfully navigate without vision through orientation and mobility training [16], they face significant challenges not faced by the sighted population [17,18,19,20]. It remains the case that human living spaces are usually designed with sighted navigation in mind [19]
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