Designing a text entry multimodal keypad for blind users of touchscreen mobile phones

In this report, we share our experience and observations on the challenges blind people face with text entry on touch-based mobile phones, particularly from the perspective of one of the authors, who is blind. To better understand these issues we developed and tested Multimodal Text Input Touchscreen Keypad (MTITK), an audio-tactile text entry prototype based on multitap, which relies on a telephone keypad layout organized into five key groups with distinct audio-tactile feedback. Users explore the screen to identify the current selected key, tap to enter text, and gesture to edit it, while receiving the corresponding voice, audio, and tactile feedback; no additional equipment is necessary in our software-only approach. We implemented a prototype on Android and tested its usability with visually impaired participants; they welcomed its multimodality and the familiar layout, but also expressed the need to increase vibration pattern differentiation and refine the character selection mechanism.