Localization of a Virtual Wall by Means of Active Echolocation by Untrained Sighted Persons

The active sensing and perception of the environment by auditory means is typically known as echolocation and it can be acquired by humans, who can profit from it in the absence of vision. We investigated the ability of twentyone untrained sighted participants to use echolocation with self-generated oral clicks for aligning themselves within the horizontal plane towards a virtual wall, emulated with an acoustic virtual reality system, at distances between 1 and 32 m, in the absence of background noise and reverberation. Participants were able to detect the virtual wall on 61% of the trials, although with large di↵erences across individuals and distances. The use of louder and shorter clicks led to an increased performance, whereas the use of clicks with lower frequency content allowed for the use of interaural time di↵erences to improve the accuracy of reflection localization at very long distances. The distance of 2 m was the most difficult to detect and localize, whereas the furthest distances of 16 and 32 m were the easiest ones. Thus, echolocation may be used e↵ectively to identify large distant environmental landmarks such as buildings

視空間支援のためのデバイスアート:人間の反響定位能力の拡張

この博士論文は全文公表に適さないやむを得ない事由があり要約のみを公表していましたが、解消したため、令和３(2021)年1月18日に全文を公表しました。筑波大学 (University of Tsukuba)201

State of the art review on walking support system for visually impaired people

The technology for terrain detection and walking support system for blind people has rapidly been improved the last couple of decades but to assist visually impaired people may have started long ago. Currently, a variety of portable or wearable navigation system is available in the market to help the blind for navigating their way in his local or remote area. The focused category in this work can be subgroups as electronic travel aids (ETAs), electronic orientation aids (EOAs) and position locator devices (PLDs). However, we will focus mainly on electronic travel aids (ETAs). This paper presents a comparative survey among the various portable or wearable walking support systems as well as informative description (a subcategory of ETAs or early stages of ETAs) with its working principal advantages and disadvantages so that the researchers can easily get the current stage of assisting blind technology along with the requirement for optimising the design of walking support system for its users

Audification of Ultrasound for Human Echolocation

Individuals with functional blindness must often utilise assistive aids to enable them to complete tasks of daily living. One of these tasks, locomotion, poses considerable risk. The long white cane is often used to perform haptic exploration, but cannot detect obstacles that are not ground-based. Although devices have been developed to provide information above waist height, these do not provide auditory interfaces that are easy to learn. Development of such devices should adapt to the user, not require adaptation by the user. Can obstacle avoidance be achieved through direct perception? This research presents an auditory interface that has been designed with the user as the primary focus. An analysis of the tasks required has been taken into account resulting in an interface that audifies ultrasound. Audification provides intuitive information to the user to enable perceptive response to environmental obstacles. A device was developed that provides Doppler shift signals that are audible as a result of intentional aliasing. This system provides acoustic flow that is evident upon initiation of travel and has been shown to be effective in perceiving apertures and avoiding environmental obstacles. The orientation of receivers on this device was also examined, resulting in better distance perception and centreline accuracy when oriented outward as compared to forward. The design of this novel user interface for visually impaired individuals has also provided a tool that can be used to evaluate direct perception and acoustic flow in a manner that has never been studied before

Blind Kcholocation

A harsh fact that half million of children go blind each year shows that blindness is one of the significant problems that require a comprehensive care. Some people might consider blindness as a sickness which blind people should be pitied and disable to perform by themselves. In other way it might leads blind people to a "life of dependence" which means that they can not do the activities as normal people can do without assist from others. This could be one of the factors that increase the unemployment rate among a blind community. Blind Echolocation is designed to meet the need of an effective way to assist the blind people to live independently with least help from other people. Although a blind person has a visually impaired but he or she still can hear an echoic sound to determine the direction and distance of the obstacles. Therefore the idea of this project is to make use of Ultrasonic Sensor to produce a device which can be a useful navigation aid for the blinds. The goal of the device is to indicate the obstacles in an environment by triggering the alarm

Sonar ultrassónico para cegos com sonificação de obstáculos

In this master’s thesis it is intended to develop a portable device that can be used by people with visual impairment in the echolocation of obstacles. This device must be capable of transmitting and detecting ultrasound signals to work as a sonar and still allow its operation as a parametric speaker capable of performing the sonification of obstacles. To do this, it was necessary to develop a Sigma-Delta ADC in FPGA that allows a high density in the independent acquisition of a large number of channels in a small device. Tests performed with the developed Sigma-Delta ADC revealed low distortion and good signal-to-noise ratio, comparable to same type ADCs available on the market. The path for the construction of the device is, then, open.Nesta tese de mestrado pretende-se desenvolver um dispositivo portátil que possa ser usado por pessoas com deficiência visual na ecolocalização de obstáculos. Este dispositivo deverá ser dotado de capacidade de emissão e deteção de ultrassons para funcionar como um sonar e permitir ainda o seu funcionamento como altifalante paramétrico capaz de realizar a sonificação dos obstáculos. Para tal, foi necessário desenvolver uma ADC Sigma-Delta em FPGA que permita uma alta densidade na aquisição independente de um grande número de canais num dispositivo de pequenas dimensões. Os testes realizados com a ADC Sigma-Delta revelaram uma baixa distorção e uma boa relação sinal ruı́do, comparáveis às ADCs do mesmo tipo existentes no mercado. Está assim preparado o caminho para a construção do dispositivo.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Effects of type of emission and masking sound, and their spatial correspondence, on blind and sighted people’s ability to echolocate

Ambient sound can mask acoustic signals. The current study addressed how echolocation in people is affected by masking sound, and the role played by type of sound and spatial (i.e. binaural) similarity. We also investigated the role played by blindness and long-term experience with echolocation, by testing echolocation experts, as well as blind and sighted people new to echolocation. Results were obtained in two echolocation tasks where participants listened to binaural recordings of echolocation and masking sounds, and either localized echoes in azimuth or discriminated echo audibility. Echolocation and masking sounds could be either clicks or broad band noise. An adaptive staircase method was used to adjust signal-to-noise ratios (SNRs) based on participants’ responses. When target and masker had the same binaural cues (i.e. both were monoaural sounds), people performed better (i.e. had lower SNRs) when target and masker used different types of sound (e.g. clicks in noise-masker or noise in clicks-masker), as compared to when target and masker used the same type of sound (e.g. clicks in click-, or noise in noise-masker). A very different pattern of results was observed when masker and target differed in their binaural cues, in which case people always performed better when clicks were the masker, regardless of type of emission used. Further, direct comparison between conditions with and without binaural difference revealed binaural release from masking only when clicks were used as emissions and masker, but not otherwise (i.e. when noise was used as masker or emission). This suggests that echolocation with clicks or noise may differ in their sensitivity to binaural cues. We observed the same pattern of results for echolocation experts, and blind and sighted people new to echolocation, suggesting a limited role played by long-term experience or blindness. In addition to generating novel predictions for future work, the findings also inform instruction in echolocation for people who are blind or sighted

Seeing with sound: Investigating the behavioural applications and neural correlates of human echolocation

Some blind humans use the reflected echoes from self-produced signals to perceive their silent surroundings. Although the use of echolocation is well documented in animals such as bats and dolphins, comparatively little is known about human echolocation. The overarching goal of the work presented in this thesis was to shed light on some of the basic functions of human echolocation, including the perception of the shape, size, and material. I addressed these aspects of echolocation using behavioural psychophysics and neuroimaging. In Chapter 2 I show that blind echolocators were able to accurately identify the shape of 2D objects, but that their ability to do so was dependent on the use of head and body movements to ‘scan’ the objects’ edges. I suggest that these scanning movements may be similar to the many saccades made by sighted individuals when visually surveying an object or scene. In Chapter 3 I addressed the possibility that object size perception via echolocation shows size constancy – a perceptual phenomenon associated with vision. The results revealed that an expert echolocator accurately perceived the true physical size of objects independent of their distance, even though changes to distance directly affect size-related echo information. The results of this study highlight the ‘visual’ nature of echolocation, and suggest further parallels between the two modalities than previously known or theorized. Chapter 4 presents the results of a functional neuroimaging study aimed at uncovering the neural correlates of material processing via echolocation. By having echolocators listen to recordings of echoes reflected from surfaces of different materials, I show not only that they can determine the material properties of objects, but also that the neural processing underlying this ability may make use of a visual- and auditory-material processing area in the parahippocampal cortex. Taken together, the work presented in the current thesis describes some of the recent contributions to our understanding of human echolocation, with a particular emphasis on its apparent parallels with vision and visual processing. The results of this work show that accurate and reliable information can be extracted from echoes, thus supporting echolocation as a viable resource for the blind