Dataset Information

Evaluation of an Audio-haptic Sensory Substitution Device for Enhancing Spatial Awareness for the Visually Impaired.

ABSTRACT: SIGNIFICANCE:Visually impaired participants were surprisingly fast in learning a new sensory substitution device, which allows them to detect obstacles within a 3.5-m radius and to find the optimal path in between. Within a few hours of training, participants successfully performed complex navigation as well as with the white cane. PURPOSE:Globally, millions of people live with vision impairment, yet effective assistive devices to increase their independence remain scarce. A promising method is the use of sensory substitution devices, which are human-machine interfaces transforming visual into auditory or tactile information. The Sound of Vision (SoV) system continuously encodes visual elements of the environment into audio-haptic signals. Here, we evaluated the SoV system in complex navigation tasks, to compare performance with the SoV system with the white cane, quantify training effects, and collect user feedback. METHODS:Six visually impaired participants received eight hours of training with the SoV system, completed a usability questionnaire, and repeatedly performed assessments, for which they navigated through standardized scenes. In each assessment, participants had to avoid collisions with obstacles, using the SoV system, the white cane, or both assistive devices. RESULTS:The results show rapid and substantial learning with the SoV system, with less collisions and higher obstacle awareness. After four hours of training, visually impaired people were able to successfully avoid collisions in a difficult navigation task as well as when using the cane, although they still needed more time. Overall, participants rated the SoV system's usability favorably. CONCLUSIONS:Contrary to the cane, the SoV system enables users to detect the best free space between objects within a 3.5-m (up to 10-m) radius and, importantly, elevated and dynamic obstacles. All in all, we consider that visually impaired people can learn to adapt to the haptic-auditory representation and achieve expertise in usage through well-defined training within acceptable time.

SUBMITTER: Hoffmann R

PROVIDER: S-EPMC6133230 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Evaluation of an Audio-haptic Sensory Substitution Device for Enhancing Spatial Awareness for the Visually Impaired.

Hoffmann Rebekka R Spagnol Simone S Kristjánsson Árni Á Unnthorsson Runar R

Optometry and vision science : official publication of the American Academy of Optometry 20180901 9

<h4>Significance</h4>Visually impaired participants were surprisingly fast in learning a new sensory substitution device, which allows them to detect obstacles within a 3.5-m radius and to find the optimal path in between. Within a few hours of training, participants successfully performed complex navigation as well as with the white cane.<h4>Purpose</h4>Globally, millions of people live with vision impairment, yet effective assistive devices to increase their independence remain scarce. A promi ...[more]

PMID: 30153241

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Project description:Understanding speech in background noise is challenging. Wearing face-masks, imposed by the COVID19-pandemics, makes it even harder. We developed a multi-sensory setup, including a sensory substitution device (SSD) that can deliver speech simultaneously through audition and as vibrations on the fingertips. The vibrations correspond to low frequencies extracted from the speech input. We trained two groups of non-native English speakers in understanding distorted speech in noise. After a short session (30-45 min) of repeating sentences, with or without concurrent matching vibrations, we showed comparable mean group improvement of 14-16 dB in Speech Reception Threshold (SRT) in two test conditions, i.e., when the participants were asked to repeat sentences only from hearing and also when matching vibrations on fingertips were present. This is a very strong effect, if one considers that a 10 dB difference corresponds to doubling of the perceived loudness. The number of sentence repetitions needed for both types of training to complete the task was comparable. Meanwhile, the mean group SNR for the audio-tactile training (14.7 ± 8.7) was significantly lower (harder) than for the auditory training (23.9 ± 11.8), which indicates a potential facilitating effect of the added vibrations. In addition, both before and after training most of the participants (70-80%) showed better performance (by mean 4-6 dB) in speech-in-noise understanding when the audio sentences were accompanied with matching vibrations. This is the same magnitude of multisensory benefit that we reported, with no training at all, in our previous study using the same experimental procedures. After training, performance in this test condition was also best in both groups (SRT ~ 2 dB). The least significant effect of both training types was found in the third test condition, i.e. when participants were repeating sentences accompanied with non-matching tactile vibrations and the performance in this condition was also poorest after training. The results indicate that both types of training may remove some level of difficulty in sound perception, which might enable a more proper use of speech inputs delivered via vibrotactile stimulation. We discuss the implications of these novel findings with respect to basic science. In particular, we show that even in adulthood, i.e. long after the classical "critical periods" of development have passed, a new pairing between a certain computation (here, speech processing) and an atypical sensory modality (here, touch) can be established and trained, and that this process can be rapid and intuitive. We further present possible applications of our training program and the SSD for auditory rehabilitation in patients with hearing (and sight) deficits, as well as healthy individuals in suboptimal acoustic situations.

Project description:In the event of visual impairment or blindness, information from other intact senses can be used as substitutes to retrain (and in extremis replace) visual functions. Abilities including reading, mental representation of objects and spatial navigation can be performed using tactile information. Current technologies can convey a restricted library of stimuli, either because they depend on real objects or renderings with low resolution layouts. Digital haptic technologies can overcome such limitations. The applicability of this technology was previously demonstrated in sighted participants. Here, we reasoned that visually-impaired and blind participants can create mental representations of letters presented haptically in normal and mirror-reversed form without the use of any visual information, and mentally manipulate such representations. Visually-impaired and blind volunteers were blindfolded and trained on the haptic tablet with two letters (either L and P or F and G). During testing, they haptically explored on any trial one of the four letters presented at 0°, 90°, 180°, or 270° rotation from upright and indicated if the letter was either in a normal or mirror-reversed form. Rotation angle impacted performance; greater deviation from 0° resulted in greater impairment for trained and untrained normal letters, consistent with mental rotation of these haptically-rendered objects. Performance was also generally less accurate with mirror-reversed stimuli, which was not affected by rotation angle. Our findings demonstrate, for the first time, the suitability of a digital haptic technology in the blind and visually-impaired. Classic devices remain limited in their accessibility and in the flexibility of their applications. We show that mental representations can be generated and manipulated using digital haptic technology. This technology may thus offer an innovative solution to the mitigation of impairments in the visually-impaired, and to the training of skills dependent on mental representations and their spatial manipulation.

Dataset Information

Evaluation of an Audio-haptic Sensory Substitution Device for Enhancing Spatial Awareness for the Visually Impaired.

Publications

Evaluation of an Audio-haptic Sensory Substitution Device for Enhancing Spatial Awareness for the Visually Impaired.

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