Usability of sensory substitution systems: test and comparison of the BrainPort and colorophone devices

PURPOSE: Sensory substitution devices (SSDs) translate information from one sensory modality into another to assist individuals with sensory impairments. This paper presents the first direct usability comparison of a visual-to-tactile SSD (BrainPort) and a visual-to-auditory SSD (Colorophone). MATERIALS AND METHODS: Two studies were conducted with visually impaired participants. The pilot study used the BrainPort V100, and the main study used the BrainPort Vision Pro; the Colorophone mobile 1.1 was used in both. Participants completed comparable training protocols for each device, followed by usability testing based on scavenger-hunt tasks in naturalistic settings (kitchen, bedroom, toilet, and park). Usability was assessed via the System Usability Scale (SUS), task completion rates, task completion times, and qualitative structured interviews. RESULTS: In both studies, the Colorophone obtained significantly higher usability scores and satisfaction ratings than the BrainPort across nearly all participants, and showed better task-level time performance. The BrainPort showed better efficacy for some kitchen-based tasks requiring greater spatial precision. Using both devices simultaneously did not enhance usability and introduced device-incoherence issues. CONCLUSIONS: The Colorophone outperformed the BrainPort on most usability metrics. Suggestions for improving usability include redesigning the devices for hygiene and aesthetics, adding automatic camera adjustments, and enhancing integration between devices for combined use. Human-centered UX methods can inform the development of more usable and widely adoptable sensory substitution solutions.