| Our goal is to explore the use of hearing and touch to convey graphical and pictorial information to visually impaired people. Our focus is on dynamic, interactive display of visual information using existing, widely available devices, such as smart phones and tablets with touch sensitive screens.;We propose a new approach for acoustic-tactile representation of visual signals that can be implemented on a touch screen and allows the user to actively explore a two-dimensional layout consisting of one or more objects with a finger or a stylus while listening to auditory feedback via stereo headphones. The proposed approach is acoustic-tactile because sound is used as the primary source of information for object localization and identification, while touch is used for pointing and kinesthetic feedback. A static overlay of raised-dot tactile patterns can also be added.;A key distinguishing feature of the proposed approach is the use of spatial sound (directional and distance cues) to facilitate the active exploration of the layout. We consider a variety of configurations for acoustic-tactile rendering of object size, shape, identity, and location, as well as for the overall perception of simple layouts and scenes. While our primary goal is to explore the fundamental capabilities and limitations of representing visual information in acoustic-tactile form, we also consider a number of relatively simple configurations that can be tied to specific applications. In particular, we consider a simple scene layout consisting of objects in a linear arrangement, each with a distinct tapping sound, which we compare to a ''virtual cane.'' We will also present a configuration that can convey a ''Venn diagram.''.;We present systematic subjective experiments to evaluate the effectiveness of the proposed display for shape perception, object identification and localization, and 2-D layout perception, as well as the applications. Our experiments were conducted with visually blocked subjects. The results are evaluated in terms of accuracy and speed, and they demonstrate the advantages of spatial sound for guiding the scanning finger or pointer in shape perception, object localization, and layout exploration. We show that these advantages increase with the amount of detail (smaller object size) in the display. Our experimental results show that the proposed system outperforms the state of the art in shape perception, including variable friction displays. We also demonstrate that, even though they are currently available only as static overlays, raised dot patterns provide the best shape rendition in terms of both the accuracy and speed. Our experiments with layout rendering and perception demonstrate that simultaneous representation of objects, using the most effective approaches for directionality and distance rendering, approaches the optimal performance level provided by visual layout perception. Finally, experiments with the virtual cane and Venn diagram configurations demonstrate that the proposed techniques can be used effectively in simple but nontrivial real-world applications.;One of the most important conclusions of our experiments is that there is a clear performance gap between experienced and inexperienced subjects, which indicates that there is a lot of room for improvement with appropriate and extensive training. By exploring a wide variety of design alternatives and focusing on different aspects of the acoustic-tactile interfaces, our results offer many valuable insights and great promise for the design of future systematic tests visually impaired and visually blocked subjects, utilizing the most effective configurations. |
