The Viking HRTF dataset

This paper describes the Viking HRTF dataset, a collection of head-related transfer functions (HRTFs) measured at the University of Iceland. The dataset includes full-sphere HRTFs measured on a dense spatial grid (1513 positions) with a KEMAR mannequin with 20 different artificial left pinnae attached, one at a time. The artificial pinnae were previously obtained through a custom molding procedure from 20 different lifelike human heads. The analyses of results reported here suggest that the collected acoustical measurements are robust, reproducible, and faithful to reference KEMAR HRTFs, and that material hardness has a negligible impact on the measurements compared to pinna shape. The purpose of the present collection, which is available for free download, is to provide accurate input data for future investigations on the relation between HRTFs and anthropometric data through machine learning techniques or other state-of-the-art methodologies

Designing sensory-substitution devices: Principles, pitfalls and potential

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

Model-based obstacle sonification for the navigation of visually impaired persons

This paper proposes a sonification model for encoding visual 3D information into sounds, inspired by the impact properties of the objects encountered during blind navigation. The proposed model is compared against two sonification models developed for orientation and mobility, chosen based on their common technical requirements. An extensive validation of the proposed model is reported; five legally blind and five normally sighted participants evaluated the proposed model as compared to the two competitive models on a simplified experimental navigation scenario. The evaluation addressed not only the accuracy of the responses in terms of psychophysical measurements but also the cognitive load and emotional stress of the participants by means of biophysiological signals and evaluation questionnaires. Results show that the proposed impact sound model adequately conveys the relevant information to the participants with low cognitive load, following a short training session

Usability and effectiveness of auditory sensory substitution models for the visually impaired

This paper focuses on auditory sensory substitution for providing visually impaired users with suitable information in both static scene recognition and dynamic obstacle avoidance. We introduce three different sonification models together with three temporal presentation schemes, i.e. ways of temporally organizing the sonic events in order to provide suitable information. Following an overview of the motivation and challenges behind each of the solutions, we describe their implementation and an evaluation of their relative strengths and weaknesses based on a set of experiments conducted in a virtual environment

Sound of vision : spatial audio output and sonification approaches

The paper summarizes a number of audio-related studies conducted by the Sound of Vision consortium, which focuses on the construction of a new prototype electronic travel aid for the blind. Different solutions for spatial audio were compared by testing sound localization accuracy in a number of setups, comparing plain stereo panning with generic and individual HRTFs, as well as testing different types of stereo headphones vs custom designed quadrophonic proximaural headphones. A number of proposed sonification approaches were tested by sighted and blind volunteers for accuracy and efficiency in representing simple virtual environments

Mechanical Characterization of Prosthetic Feet and Shell Covers Using a Force Loading Apparatus

To assist in the redirection of kinetic energy many modern prosthetic feet often utilize a so called energy storing and return (ESAR) design that is achieved through dorsiflexion and elastic bending to facilitate forward propulsion during push-off. Consequently, the proper selection of the foot stiffness and mechanical response for an individual amputee is significant; however, the component stiffness and mechanical properties between manufactures remains largely unreported. This study reports independent characterization of TLM Prosthetics TaiLor Made foot with interchangeable springs and Freedom Innovations Renegade foot using mechanical testing techniques to determine the stiffness, viscoelasticity, and localized material strain in prosthetic feet and their cosmetic covers. Mechanical data are acquired during the compressive loading of the prosthetic foot via force-deflection sensors and digital image correlation. In doing so, this contribution demonstrates a curtailed characterization process that can be used to quantify properties for other modern foot prosthetics