How much spatial information is lost in the sensory substitution process? Comparing visual, tactile, and auditory approaches

Sensory substitution devices (SSDs) can convey visuospatial information through spatialised auditory or tactile stimulation using wearable technology. However, the level of information loss associated with this transformation is unknown. In this study novice users discriminated the location of two objects at 1.2m using devices that transformed a 16x 8 depth map into spatially distributed patterns of light, sound, or touch on the abdomen. Results showed that through active sensing, participants could discriminate the vertical position of objects to a visual angle of 1°, 14°, and 21°, and their distance to 2cm, 8cm, and 29cm using these visual, auditory, and haptic SSDs respectively. Visual SSDs significantly outperformed auditory and tactile SSDs on vertical localisation, whereas for depth perception, all devices significantly differed from one another (visual > auditory > haptic). Our findings highlight the high level of acuity possible for SSDs even with low spatial resolutions (e.g. 16 8) and quantify the level of information loss attributable to this transformation for the SSD user. Finally, we discuss ways of closing this ‘modality gap’ found in SSDs and conclude that this process is best benchmarked against performance with SSDs that return to their primary modality (e.g. visuospatial into visual)

Stochastic Resonance Reduces Sway and Gait Variability in Individuals With Unilateral Transtibial Amputation: A Pilot Study

Sub-threshold (imperceptible) vibration, applied to parts of the body, impacts how people move and perceive our world. Could this idea help someone who has lost part of their limb? Sub-threshold vibration was applied to the thigh of the affected limb of 20 people with unilateral transtibial amputation. Vibration conditions tested included two noise structures: pink and white. Center of pressure (COP) excursion (range and root-mean-square displacements) during quiet standing, and speed and spatial stride measures (mean and standard deviations of step length and width) during walking were assessed. Pink noise vibration decreased COP displacements in standing, and white noise vibration decreased sound limb step length standard deviation in walking. Sub-threshold vibration positively impacted aspects of both posture and gait; however, different noise structures had different effects. The current study represents foundational work in understanding the potential benefits of incorporating stochastic resonance as an intervention for individuals with amputation

Investigating perceptual congruence between information and sensory parameters in auditory and vibrotactile displays

A fundamental interaction between a computer and its user(s) is the transmission of information between the two and there are many situations where it is necessary for this interaction to occur non-visually, such as using sound or vibration. To design successful interactions in these modalities, it is necessary to understand how users perceive mappings between information and acoustic or vibration parameters, so that these parameters can be designed such that they are perceived as congruent. This thesis investigates several data-sound and data-vibration mappings by using psychophysical scaling to understand how users perceive the mappings. It also investigates the impact that using these methods during design has when they are integrated into an auditory or vibrotactile display. To investigate acoustic parameters that may provide more perceptually congruent data-sound mappings, Experiments 1 and 2 explored several psychoacoustic parameters for use in a mapping. These studies found that applying amplitude modulation — or roughness — to a signal, or applying broadband noise to it resulted in performance which were similar to conducting the task visually. Experiments 3 and 4 used scaling methods to map how a user perceived a change in an information parameter, for a given change in an acoustic or vibrotactile parameter. Experiment 3 showed that increases in acoustic parameters that are generally considered undesirable in music were perceived as congruent with information parameters with negative valence such as stress or danger. Experiment 4 found that data-vibration mappings were more generalised — a given increase in a vibrotactile parameter was almost always perceived as an increase in an information parameter — regardless of the valence of the information parameter. Experiments 5 and 6 investigated the impact that using results from the scaling methods used in Experiments 3 and 4 had on users' performance when using an auditory or vibrotactile display. These experiments also explored the impact that the complexity of the context which the display was placed had on user performance. These studies found that using mappings based on scaling results did not significantly impact user's performance with a simple auditory display, but it did reduce response times in a more complex use-case

ヒトの高周波振動知覚の類似特性に基づく触覚変調

Tohoku University昆陽雅司課

Ayuda técnica para la autonomía en el desplazamiento

The project developed in this thesis involves the design, implementation and evaluation of a new technical assistance aiming to ease the mobility of people with visual impairments. By using processing and sounds synthesis, the users can hear the sonification protocol (through bone conduction) informing them, after training, about the position and distance of the various obstacles that may be on their way, avoiding eventual accidents. In this project, surveys were conducted with experts in the field of rehabilitation, blindness and techniques of image processing and sound, which defined the user requirements that served as guideline for the design. The thesis consists of three self-contained blocks: (i) image processing, where 4 processing algorithms are proposed for stereo vision, (ii) sonification, which details the proposed sound transformation of visual information, and (iii) a final central chapter on integrating the above and sequentially evaluated in two versions or implementation modes (software and hardware). Both versions have been tested with both sighted and blind participants, obtaining qualitative and quantitative results, which define future improvements to the project. ---------------------------------------------------------------------------------------------------------------------------------------------El proyecto desarrollado en la presente tesis doctoral consiste en el diseño, implementación y evaluación de una nueva ayuda técnica orientada a facilitar la movilidad de personas con discapacidad visual. El sistema propuesto consiste en un procesador de estereovisión y un sintetizador de sonidos, mediante los cuales, las usuarias y los usuarios pueden escuchar un código de sonidos mediante transmisión ósea que les informa, previo entrenamiento, de la posición y distancia de los distintos obstáculos que pueda haber en su camino, evitando accidentes. En dicho proyecto, se han realizado encuestas a expertos en el campo de la rehabilitación, la ceguera y en las técnicas y tecnologías de procesado de imagen y sonido, mediante las cuales se definieron unos requisitos de usuario que sirvieron como guía de propuesta y diseño. La tesis está compuesta de tres grandes bloques autocontenidos: (i) procesado de imagen, donde se proponen 4 algoritmos de procesado de visión estéreo, (ii) sonificación, en el cual se detalla la propuesta de transformación a sonido de la información visual, y (iii) un último capítulo central sobre integración de todo lo anterior en dos versiones evaluadas secuencialmente, una software y otra hardware. Ambas versiones han sido evaluadas con usuarios tanto videntes como invidentes, obteniendo resultados cualitativos y cuantitativos que permiten definir mejoras futuras sobre el proyecto finalmente implementado