Sonified distance in sensory substitution does not always improve localization: comparison with a 2D and 3D handheld device

TL;DR

This study compares 2D and 3D sensory substitution devices for object localization and navigation, finding that adding distance information improves localization speed but does not significantly enhance navigation performance.

Contribution

It provides empirical evidence on the effectiveness of 3D distance encoding in sensory substitution devices for different spatial tasks.

Findings

3D mode improves localization speed initially

Participants compensate for lack of distance info after training

No significant difference in navigation performance between modes

Abstract

Early visual to auditory substitution devices encode 2D monocular images into sounds while more recent devices use distance information from 3D sensors. This study assesses whether the addition of sound-encoded distance in recent systems helps to convey the "where" information. This is important to the design of new sensory substitution devices. We conducted experiments for object localization and navigation tasks with a handheld visual to audio substitution system. It comprises 2D and 3D modes. Both encode in real-time the position of objects in images captured by a camera. The 3D mode encodes in addition the distance between the system and the object. Experiments have been conducted with 16 blindfolded sighted participants. For the localization, participants were quicker to understand the scene with the 3D mode that encodes distances. On the other hand, with the 2D only mode, they were able to compensate for the lack of distance encoding after a small training. For the navigation, participants were as good with the 2D only mode than with the 3D mode encoding distance.