Stimulus order has been reported to affect perceived loudness. This letter investigates how temporal order affects distance discrimination of receding and approaching pairs of sound sources rendered binaurally in the anechoic near-field. Individual discrimination thresholds for different virtual locations were measured through an adaptive procedure. The threshold values show a bias toward approaching stimuli for closer reference distances (≤50 cm) and toward receding stimuli for farther reference distances (100 cm), but only when absolute intensity cues are available. The results show how an illusion of loudness can translate into an illusion of perceived relative distance. ; This project was supported by the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 643636. ; Peer Reviewed
Translating visual representations of real environments into auditory feedback is one of the key challenges in the design of an electronic travel aid for visually impaired persons. Although the solutions currently available in the literature can lead to effective sensory substitution, high commitment to an extensive training program involving repetitive sonic patterns is typically required, undermining their use in everyday life. The current study explores a novel sensory substitution algorithm that extracts information from raw depth maps and continuously converts it into parameters of a naturally sounding, physically based liquid sound model describing a population of bubbles. This approach is tested in a simplified wayfinding experiment with 14 blindfolded sighted participants and compared against the most popular sensory substitution algorithm available in the literature – the vOICe (Meijer, 1992) – following a short-time training program. The results indicate a superior performance of the proposed sensory substitution algorithm in terms of navigation accuracy, intuitiveness and pleasantness of the delivered sounds compared to the vOICe algorithm. These results should be applied to the visually impaired population with caution. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 643636. ; Peer Reviewed
Electronic travel aids (ETAs) have been in focus since technology allowed designing relatively small, light, and mobile devices for assisting the visually impaired. Since visually impaired persons rely on spatial audio cues as their primary sense of orientation, providing an accurate virtual auditory representation of the environment is essential. This paper gives an overview of the current state of spatial audio technologies that can be incorporated in ETAs, with a focus on user requirements. Most currently available ETAs either fail to address user requirements or underestimate the potential of spatial sound itself, which may explain, among other reasons, why no single ETA has gained a widespread acceptance in the blind community. We believe there is ample space for applying the technologies presented in this paper, with the aim of progressively bridging the gap between accessibility and accuracy of spatial audio in ETAs. ; This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement no. 643636. ; Peer Reviewed
An exciting possibility for compensating for loss of sensory function is to augment deficient senses by conveying missing information through an intact sense. Here we present an overview of techniques that have been developed for sensory substitution (SS) for the blind, through both touch and audition, with special emphasis on the importance of training for the use of such devices, while highlighting potential pitfalls in their design. One example of a pitfall is how conveying extra information about the environment risks sensory overload. Related to this, the limits of attentional capacity make it important to focus on key information and avoid redundancies. Also, differences in processing characteristics and bandwidth between sensory systems severely constrain the information that can be conveyed. Furthermore, perception is a continuous process and does not involve a snapshot of the environment. Design of sensory substitution devices therefore requires assessment of the nature of spatiotemporal continuity for the different senses. Basic psychophysical and neuroscientific research into representations of the environment and the most effective ways of conveying information should lead to better design of sensory substitution systems. Sensory substitution devices should emphasize usability, and should not interfere with other inter- or intramodal perceptual function. Devices should be task-focused since in many cases it may be impractical to convey too many aspects of the environment. Evidence for multisensory integration in the representation of the environment suggests that researchers should not limit themselves to a single modality in their design. Finally, we recommend active training on devices, especially since it allows for externalization, where proximal sensory stimulation is attributed to a distinct exterior object. ; This work was supported by the European Union's Horizon 2020 Research and Innovative Programme under grant agreement no. 643636, "Sound of Vision". ; Peer Reviewed
