Assistive Technology for Visually Impaired and Blind People (eBook)

Dr Hersh is currently a senior Lecturer in the Department of Electronics and Electrical Engineering, University of Glasgow. She was previously a lecturer in this Department. She has also held posts as a Post-doctoral Research Fellow at the Universities of Sussex and Strathclyde. She has now been researching in the area of assistive technology for about 12 years. Her current research interests fall into four main areas: • Assistive technology, particularly for people with sensory impairments. • Ethics and Social Responsibility Issues in Science and Engineering. • Good design practice, including the principles of sustainable and universal design, end user involvement and human centred design approaches. • The research process. She is continuing to run the successful CVHI conference series ‘Conference and Workshop on Assistive Technologies for People with Vision and Hearing Impairments’, which she initiated with Prof Mike Johnson of the University of Strathclyde. Funding for the first three events was obtained from the EC High-Level Scientific Conferences Programme and the current funding for three further events, of which one has already taken place. Distinctive features of this conference series include the support given to young researchers and the conference ambience which encourages networking. Current research projects in the area of assistive technology include the development of a communication and interface device for deafblind people, distance learning for people with mobility impairments with colleagues from Germany, Hungary and Romania and travel support technology for blind people with colleagues from France. Having been a workaholic for most of her life, Dr Hersh has recently become aware of the importance of making leisure activities accessible. Research carried out for the book has confirmed the lack of technology to support the involvement of blind people in sport and other leisure activities. Research projects in this area include technological support for learning swimming and cycling in quiet areas for blind people. Dr Hersh recently published Mathematical Modelling for Sustainable Development with Springer Verlag (2006). It is organised into three parts, each of which considers the application of a particular type of mathematical or computing technique to problems in sustainable development. Particular features of the book include the large number of examples of the application of the techniques to problems in sustainable development, the detailed case studies, for instance of the application of systems theory to sustainable waste management and the introduction of fuzzy set techniques she developed. She has worked on applications of these techniques in collaboration with colleagues from Germany and Romania. Dr Hersh’s awareness of the importance of interdisciplinarity for successful research in assistive technology has led her to an examination of the research process and publications on interdisciplinary work and research cultures with colleagues from Wales. Dr Hersh is a Member of the Institute of Mathematics and its Applications, the Institution of Engineering and Technology (UK) and the Institute of Electronic and Electrical Engineers (USA). Professor Johnson’s academic career has concentrated on control engineering, theory and applications. He has significant industrial control applications and research experience. He is the author and co-author of books and technical papers on power generation, wastewater control, power transmission, and control benchmarking. He has had a number of student projects in the area of assistive technology and has successfully trained over 40 engineers to PhD level in last 20 years. He is joint Editor to Springer-Verlag-London monograph series Advances in Industrial Control and to the Springer-Verlag-London Advanced Textbooks in Control and Signal Processing series. He was an Associate Editor for Automatica in the years 1985-2002. His interest in Assistive Technology came through undergraduate teaching commitments which included student group study dissertations at 2nd Year level and assorted project supervision at Masters and undergraduate level. These were used to explore some EEE aspects of assistive devices for the hearing impaired. Subsequent collaboration with Dr. Hersh at the University of Glasgow led to a set of targeted activities in this area. These include a new course module, a new conference series and some research projects. Professor Johnson retired from academic life in 2002 and was made an Emeritus Professor of the University of Strathclyde in 2003. Emeritus Professor Johnson is a member of Deafblind, UK and the British Retinitis Pigmentosa Society.

Preface 6
Contents 17
1 Disability and Assistive Technology Systems 28
Learning Objectives 28
1.1 The Social Context of Disability 29
1.2 Assistive Technology Outcomes: Quality of Life 31
1.2.1 Some General Issues 32
1.2.2 Definition and Measurement of Quality of Life 33
1.2.3 Health Related Quality of Life Measurement 34
1.2.4 Assistive Technology Quality of Life Procedures 36
1.2.5 Summary and Conclusions 40
1.3 Modelling Assistive Technology Systems 41
1.3.1 Modelling Approaches: A Review 42
1.3.2 Modelling Human Activities 45
1.4 The Comprehensive Assistive Technology (CAT) Model 47
1.4.1 Justification of the Choice of Model 47
1.4.2 The Structure of the CAT Model 48
1.5 Using the Comprehensive Assistive Technology Model 63
1.5.1 Using the Activity Attribute of the CAT Model to Determine Gaps in Assistive Technology Provision 64
1.5.2 Conceptual Structure of Assistive Technology Systems 65
1.5.3 Investigating Assistive Technology Systems 65
1.5.4 Analysis of Assistive Technology Systems 67
1.5.5 Synthesis of Assistive Technology Systems 68
1.6 Chapter Summary 72
Questions 73
Projects 74
References 75
2 Perception, the Eye and Assistive Technology Issues 78
Learning Objectives 78
2.1 Perception 79
2.1.1 Introduction 79
2.1.2 Common Laws and Properties of the Different Senses 80
2.1.3 Multisensory Perception 81
2.1.4 Multisensory Perception in the Superior Colliculus 84
2.1.5 Studies of Multisensory Perception 85
2.2 The Visual System 85
2.2.1 Introduction 85
2.2.2 The Lens 87
2.2.3 The Iris and Pupil 88
2.2.4 Intraocular Pressure 89
2.2.5 Extraocular Muscles 90
2.2.6 Eyelids and Tears 92
2.3 Visual Processing in the Retina, Laternal Geniculate Nucleus and the Brain 92
2.3.1 Nerve Cells 92
2.3.2 The Retina 94
2.3.3 The Optic Nerve, Optic Tract and Optic Radiation 96
2.3.4 The Lateral Geniculate Body or Nucleus 98
2.3.5 The Primary Visual or Striate Cortex 98
2.3.6 The Extrastriate Visual Cortex and the Superior Colliculus 99
2.3.7 Visual Pathways 100
2.4 Vision in Action 101
2.4.1 Image Formation 101
2.4.2 Accommodation 103
2.4.3 Response to Light 103
2.4.4 Colour Vision 104
2.4.5 Binocular Vision and Stereopsis 109
2.5 Visual Impairment and Assistive Technology 109
2.5.1 Demographics of Visual Impairment 110
2.5.2 Illustrations of Some Types of Visual Impairment 111
2.5.3 Further Types of Visual Impairment 118
2.5.4 Colour Blindness 120
2.5.5 Corrective Lenses 121
2.6 Chapter Summary 125
Questions 126
Projects 126
References 126
3 Sight Measurement 129
Learning Objectives 129
3.1 Introduction 129
3.2 Visual Acuity 130
3.2.1 Using the Chart 131
3.2.2 Variations in Measuring Visual Acuity 131
3.3 Field of Vision Tests 133
3.3.1 The Normal Visual Field 133
3.3.2 The Tangent Screen 134
3.3.3 Kinetic Perimetry 134
3.3.4 Static Perimetry 136
3.4 Pressure Measurement 137
3.5 Biometry 138
3.6 Ocular Examination 139
3.7 Optical Coherence Tomography 140
3.7.1 Echo Delay 142
3.7.2 Low Coherence Interferometry 142
3.7.3 An OCT Scanner 143
3.8 Ocular Electrophysiology 144
3.8.1 The Electrooculogram (EOG) 146
3.8.2 The Electroretinogram (ERG) 149
3.8.3 The Pattern Electroretinogram 152
3.8.4 The Visual Evoked Cortical Potential 153
3.8.5 Multifocal Electrophysiology 153
3.9 Chapter Summary 158
Glossary 158
Questions 159
Projects 159
Reference Sources 159
4 Haptics as a Substitute for Vision 160
Learning Objectives 160
4.1 Introduction 160
4.1.1 Physiological Basis 161
4.1.2 Passive Touch, Active Touch and Haptics 162
4.1.3 Exploratory Procedures 162
4.2 Vision and Haptics Compared 163
4.3 The Capacity of Bare Fingers in Real Environments 164
4.3.1 Visually Impaired People’s Use of Haptics Without any Technical Aid 165
4.3.2 Speech Perceived by Hard-of-hearing People Using Bare Hands 165
4.3.3 Natural Capacity of Touch and Evaluation of Technical Aids 166
4.4 Haptic Low-tech Aids 166
4.4.1 The Long Cane 166
4.4.2 The Guide Dog 167
4.4.3 Braille 168
4.4.4 Embossed Pictures 169
4.4.5 The Main Lesson from Low-tech Aids 170
4.5 Matrices of Point Stimuli 170
4.5.1 Aids for Orientation and Mobility 170
4.5.2 Aids for Reading Text 173
4.5.3 Aids for Reading Pictures 174
4.6 Computer-based Aids for Graphical Information 174
4.6.1 Aids for Graphical User Interfaces 175
4.6.2 Tactile Computer Mouse 175
4.7 Haptic Displays 176
4.7.1 Information Available via a Haptic Display 177
4.7.2 What Information Can Be Obtained with the Reduced Information? 178
4.7.3 Haptic Displays as Aids for the Visually Impaired 181
4.8 Chapter Summary 183
4.9 Concluding Remarks 184
Questions 184
Projects 184
References 185
5 Mobility: An Overview 192
Learning Objectives 192
5.1 Introduction 193
5.2 The Travel Activity 194
5.2.1 Understanding Mobility 194
5.2.2 Assistive Technology Systems for the Travel Process 198
5.3 The Historical Development of Travel Aids for Visually Impaired and Blind People 202
5.4 Obstacle Avoidance AT: Guide Dogs and Robotic Guide Walkers 205
5.4.1 Guide Dogs 205
5.4.2 Robotic Guides and Walkers 206
5.5 Obstacle Avoidance AT: Canes 210
5.5.1 Long Canes 211
5.5.2 Technology Canes 212
5.6 Other Mobility Assistive Technology Approaches 216
5.6.1 Clear-path Indicators 217
5.6.2 Obstacle and Object Location Detectors 219
5.6.3 The vOICe System 222
5.7 Orientation Assistive Technology Systems 223
5.7.1 Global Positioning System Orientation Technology 225
5.7.2 Other Technology Options for Orientation Systems 225
5.8 Accessible Environments 226
5.9 Chapter Summary 230
Questions 232
Projects 232
References 232
6 Mobility AT: The Batcane (UltraCane) 234
Learning Objectives 234
6.1 Mobility Background and Introduction 234
6.2 Principles of Ultrasonics 235
6.2.1 Ultrasonic Waves 235
6.2.2 Attenuation and Reflection Interactions 236
6.2.3 Transducer Geometry 237
6.3 Bats and Signal Processing 238
6.3.1 Principles of Bat Sonar 238
6.3.2 Echolocation Call Structures 240
6.3.3 Signal Processing Capabilities 241
6.3.4 Applicability of Bat Echolocation to Sonar System Design 242
6.4 Design and Construction Issues 243
6.4.1 Outline Requirement Specification 243
6.4.2 Ultrasonic Spatial Sensor Subsystem 244
6.4.3 Trial Prototype Spatial Sensor Arrangement 244
6.4.4 Tactile User Interface Subsystem 246
6.4.5 Cognitive Mapping 247
6.4.6 Embedded Processing Control Requirements 248
6.5 Concept Phase and Engineering Prototype Phase Trials 248
6.6 Case Study in Commercialisation 250
6.7 Chapter Summary 251
Questions 252
Projects 252
References 254
7 Navigation AT: Context-aware Computing 255
Learning objectives 255
7.1 Defining the Orientation/Navigation Problem 255
7.1.1 Orientation, Mobility and Navigation 256
7.1.2 Traditional Mobility Aids 257
7.1.3 Limitations of Traditional Aids 257
7.2 Cognitive Maps 258
7.2.1 Learning and Acquiring Spatial Information 259
7.2.2 Factors that Influence How Knowledge Is Acquired 260
7.2.3 The Structure and Form of Cognitive Maps 261
7.3 Overview of Existing Technologies 262
7.3.1 Technologies for Distant Navigation 262
7.3.2 User Interface Output Technologies 263
7.4 Principles of Mobile Context-aware Computing 264
7.4.1 Adding Context to User-computer Interaction 265
7.4.2 Acquiring Useful Contextual Information 266
7.4.3 Capabilities of Context-awareness 268
7.4.4 Application of Context-aware Principles 269
7.4.5 Technological Challenges and Unresolved Usability Issues 272
7.5 Test Procedures 273
7.5.1 Human Computer Interaction (HCI) 273
7.5.2 Cognitive Mapping 276
7.5.3 Overall Approach 277
7.6 Future Positioning Technologies 277
7.7 Chapter Summary 279
7.7.1 Conclusions 280
Questions 281
Projects 282
References 282
8 Accessible Global Positioning System (GPS) and Related Orientation Technologies 285
Learning Objectives 285
8.1 Defining the Navigation Problem 285
8.1.1 What is the Importance of Location Information? 286
8.1.2 What Mobility Tools and Traditional Maps are Available for the Blind? 287
8.2 Principles of Global Positioning Systems 287
8.2.1 What is the Global Positioning System? 287
8.2.2 Accuracy of GPS: Some General Issues 289
8.2.3 Accuracy of GPS: Some Technical Issues 291
8.2.4 Frequency Spectrum of GPS, Present and Future 293
8.2.5 Other GPS Systems 294
8.3 Application of GPS Principles 296
8.4 Design Issues 297
8.5 Development Issues 302
8.5.1 Choosing an Appropriate Platform 302
8.5.2 Choosing the GPS Receiver 303
8.5.3 Creating a Packaged System 303
8.5.4 Integration vs Stand-alone 304
8.6 User Interface Design Issues 305
8.6.1 How to Present the Information 305
8.6.2 When to Present the Information 306
8.6.3 What Information to Present 306
8.7 Test Procedures and Results 307
8.8 Case Study in Commercialisation 307
8.8.1 Understanding the Value of the Technology 307
8.8.2 Limitations of the Technology 308
8.8.3 Ongoing Development 309
8.9 Chapter Summary 310
Questions 311
Projects 311
References 311
9 Electronic Travel Aids: An Assessment 313
Learning Objectives 313
9.1 Introduction 314
9.2 Why Do an Assessment? 315
9.3 Methodologies for Assessments of Electronic Travel Aids 316
9.3.1 Eliciting User Requirements 316
9.3.2 Developing a User Requirements Specification and Heuristic Evaluation 318
9.3.3 Hands-on Assessments 319
9.3.4 Methodology Used for Assessments in this Chapter 319
9.4 Modern-day Electronic Travel Aids 323
9.4.1 The Distinction Between Mobility and Navigation Aids 324
9.4.2 The Distinction Between Primary and Secondary Aids 324
9.4.3 User Requirements: Mobility and Navigation Aids 324
9.4.4 Mobility Aids 328
9.4.5 Mobility Aids: Have They Solved the Mobility Challenge? 335
9.4.6 Navigation Aids 336
9.4.7 Navigation Aids: Have They Solved the Navigation Challenge? 338
9.5 Training 339
9.6 Chapter Summary and Conclusions 341
Questions 342
Projects 343
References 344
10 Accessible Environments 346
Learning Objectives 346
10.1 Introduction 346
10.1.1 Legislative and Regulatory Framework 346
10.1.2 Accessible Environments: An Overview 348
10.1.3 Principles for the Design of Accessible Environments 349
10.1.4 Relationship Between Environmental Information and Navigation Systems and Global Positioning Systems (GPS) Orientation Systems 350
10.2 Physical Environments: The Streetscape 351
10.2.1 Pavements and Pathways 351
10.2.2 Road Crossings 353
10.2.3 Bollards and Street Furniture 354
10.3 Physical Environments: Buildings 356
10.3.1 General Exterior Issues 357
10.3.2 General Interior Issues 358
10.3.3 Lighting and Décor 361
10.3.4 Signs and Notices 366
10.3.5 Interior Building Services 368
10.4 Environmental Information and Navigation Technologies 371
10.4.1 Audio Information System: General Issues 371
10.4.2 Some Technologies for Environmental Information Systems 373
10.5 Accessible Public Transport 377
10.5.1 Accessible Public Transportation: Design Issues 378
10.5.2 Accessible Public Transportation: Technological Information and Way-finding Systems 379
10.6 Chapter Summary 381
Questions 382
Projects 383
References 383
11 Accessible Bus System: A Bluetooth Application 385
Learning Objectives 385
11.1 Introduction 385
11.2 Bluetooth Fundamentals 386
11.2.1 Brief History of Bluetooth 386
11.2.2 Bluetooth Power Class 386
11.2.3 Protocol Stack 387
11.2.4 Bluetooth Profile 387
11.2.5 Piconet 388
11.2.6 Bluetooth and Competing Wireless Technol 388
11.3 Design Issues 389
11.3.1 System Architecture 390
11.3.2 Hardware Requirements 391
11.3.3 Software Requirements 391
11.4 Developmental Issues 394
11.4.1 Bluetooth Server 395
11.4.2 Bluetooth Client (Mobile Device) 399
11.4.3 User Interface 401
11.5 Commercialisation Issues 403
11.6 Chapter Summary 404
Questions 404
Projects 405
References 406
12 Accessible Information: An Overview 407
Learning Objectives 407
12.1 Introduction 408
12.2 Low Vision Aids 409
12.2.1 Basic Principles 409
12.3 Low Vision Assistive Technology Systems 413
12.3.1 Large Print 414
12.3.2 Closed Circuit Television Systems 415
12.3.3 Video Magnifiers 417
12.3.4 Telescopic Assistive Systems 418
12.4 Audio-transcription of Printed Information 423
12.4.1 Stand-alone Reading Systems 423
12.4.2 Read IT Project 425
12.5 Tactile Access to Information 429
12.5.1 Braille 429
12.5.2 Moon 430
12.5.3 Braille Devices 430
12.6 Accessible Computer Systems 432
12.6.1 Input Devices 436
12.6.2 Output Devices 439
12.6.3 Computer-based Reading Systems 443
12.6.4 Accessible Portable Computers 444
12.7 Accessible Internet 445
12.7.1 World Wide Web Guidelines 446
12.7.2 Guidelines for Web Authoring Tools 452
12.7.3 Accessible Adobe Portable Document Format (PDF) Documents 456
12.7.4 Bobby Approval 459
12.8 Telecommunications 460
12.8.1 Voice Dialling General Principles 460
12.8.2 Talking Caller ID 463
12.8.3 Mobile Telephones 464
12.9 Chapter Summary 466
Questions 467
Projects 468
References 469
13 Screen Readers and Screen Magnifiers 471
Learning Objectives 471
13.1 Introduction 471
13.2 Overview of Chapter 472
13.3 Interacting with a Graphical User Interface 473
13.4 Screen Magnifiers 475
13.4.1 Overview 475
13.4.2 Magnification Modes 476
13.4.3 Other Interface Considerations 484
13.4.4 The Architecture and Implementation of Screen Magnifiers 488
13.5 Screen Readers 500
13.5.1 Overview 500
13.5.2 The Architecture and Implementation of a Screen Reader 502
13.5.3 Using a Braille Display 507
13.5.4 User Interface Issues 508
13.6 Hybrid Screen Reader Magnifiers 511
13.7 Self-magnifying Applications 511
13.8 Self-voicing Applications 511
13.9 Application Adaptors 513
13.10 Chapter Summary 513
Questions 514
Projects 514
References 517
14 Speech, Text and Braille Conversion Technology 518
Learning Objectives 518
14.1 Introduction 518
14.1.1 Introducing Mode Conversion 518
14.1.2 Outline of the Chapter 520
14.2 Prerequisites for Speech and Text Conversion Technology 521
14.2.1 The Spectral Structure of Speech 521
14.2.2 The Hierarchical Structure of Spoken Language 526
14.2.3 Prosody 529
14.3 Speech-to-text Conversion 530
14.3.1 Principles of Pattern Recognition 530
14.3.2 Principles of Speech Recognition 536
14.3.3 Equipment and Applications 538
14.4 Text-to-speech Conversion 542
14.4.1 Principles of Speech Production 542
14.4.2 Principles of Acoustical Synthesis 543
14.4.3 Equipment and Applications 546
14.5 Braille Conversion 549
14.5.1 Introduction 549
14.5.2 Text-to-Braille Conversion 552
14.5.3 Braille-to-text Conversion 556
14.6 Commercial Equipment and Applications 558
14.6.1 Speech vs Braille 558
14.6.2 Speech Output in Devices for Daily Life 559
14.6.3 Portable Text-based Devices 561
14.6.4 Access to Computers 561
14.6.5 Reading Machines 563
14.6.6 Access to Telecommunication Devices 564
14.7 Discussion and the Future Outlook 564
14.7.1 End-user Studies 564
14.7.2 Discussion and Issues Arising 566
14.7.3 Future Developments 567
Questions 570
Projects 570
References 572
15 Accessing Books and Documents 576
Learning Objectives 576
15.1 Introduction: The Challenge of Accessing the Printed Page 576
15.2 Basics of Optical Character Recognition Technology 578
15.2.1 Details of Optical Character Recognition Technology 579
15.2.2 Practical Issues with Optical Character Recognition Technology 582
15.3 Reading Systems 583
15.4 DAISY Technology 586
15.4.1 DAISY Full Audio Books 588
15.4.2 DAISY Full Text Books 589
15.4.3 DAISY and Other Formats 590
15.5 Players 592
15.6 Accessing Textbooks 595
15.7 Accessing Newspapers 596
15.8 Future Technology Developments 597
15.9 Chapter Summary and Conclusion 598
15.9.1 Chapter Summary 598
15.9.2 Conclusion 599
Questions 599
Projects 599
References 600
16 Designing Accessible Music Software for Print Impaired People 602
Learning Objectives 602
16.1 Introduction 603
16.1.1 Print Impairments 603
16.1.2 Music Notation 604
16.2 Overview of Accessible Music 605
16.2.1 Formats 605
16.2.2 Technical Aspects 614
16.3 Some Recent Initiatives and Projects 615
16.3.1 InteractiveMusic Network 615
16.3.2 Play 2 616
16.3.3 Dancing Dots 617
16.3.4 Toccata 618
16.4 Problems to Be Overcome 618
16.4.1 A Content Processing Layer 619
16.4.2 Standardization of Accessible Music Technology 620
16.5 Unifying Accessible Design, Technology and Musical Content 621
16.5.1 Braille Music 621
16.5.2 Talking Music 628
16.6 Conclusions 630
16.6.1 Design for All or Accessibility from Scratch 631
16.6.2 Applying Design for All in Emerging Standards 631
16.6.3 Accessibility in Emerging Technology 632
Questions 632
Projects 632
References 633
17 Assistive Technology for Daily Living 635
Learning Objectives 635
17.1 Introduction 636
17.2 Personal Care 637
17.2.1 Labelling Systems 637
17.2.2 Healthcare Monitoring 645
17.3 Time-keeping, Alarms and Alerting 648
17.3.1 Time-keeping 648
17.3.2 Alarms and Alerting 650
17.4 Food Preparation and Consumption 653
17.4.1 Talking Kitchen Scales 653
17.4.2 Talking Measuring Jug 654
17.4.3 Liquid Level Indicator 655
17.4.4 Talking Microwave Oven 655
17.4.5 Talking Kitchen and Remote Thermometers 655
17.4.6 Braille Salt and Pepper Set 656
17.5 Environmental Control and Use of Appliances 656
17.5.1 Light Probes 657
17.5.2 Colour Probes 659
17.5.3 Talking and Tactile Thermometers and Barometers 661
17.5.4 Using Appliances 662
17.6 Money, Finance and Shopping 663
17.6.1 Mechanical Money Indicators 664
17.6.2 Electronic Money Identifiers 665
17.6.3 Electronic Purse 665
17.6.4 Automatic Teller Machines (ATMs) 667
17.7 Communications and Access to Information: Other Technologies 668
17.7.1 Information Kiosks and Other Self-service Systems 668
17.7.2 Using Smart Cards 670
17.7.3 EZ Access® 672
17.8 Chapter Summary 673
Questions 675
Projects 675
References 676
18 Assistive Technology for Education, Employment and Recreation 678
Learning Objectives 678
18.1 Introduction 678
18.2 Education: Learning and Teaching 680
18.2.1 Accessing Educational Processes and Approaches 681
18.2.2 Educational Technologies, Devices and Tools 686
18.3 Employment 689
18.3.1 Professional and Person-centred 690
18.3.2 Scientific and Technical 692
18.3.3 Administrative and Secretarial 693
18.3.4 Skilled and Non-skilled (Manual) Trades 695
18.3.5 Working Outside 699
18.4 Recreational Activities 699
18.4.1 Accessing the Visual, Audio and Performing Arts 700
18.4.2 Games, Puzzles, Toys and Collecting 705
18.4.3 Holidays and Visits: Museums, Galleries and Heritage Sites 706
18.4.4 Sports and Outdoor Activities 707
18.4.5 DIY, Art and Craft Activities 715
18.5 Chapter Summary 719
Questions 721
Projects 721
References 722
Biographical Sketches of the Contributors 727
Index 735

"12 Accessible Information: An Overview (p. 385-386)

Learning Objectives

Increasingly complex media and technology are being used to transmit information. However, a degree of familiarity with new technological developments is required to make the best use of information media and technologies, so it is important that this area remains accessible to the visually impaired and blind community. It should be noted that there are currently many people who either do not have access tomodern communications and information technology or do not wish to use it. It is therefore important that information continues to be provided in other lower tech and more traditional ways.

This chapter openswith a review of the principles and technologies of lowvision aids that are used to access print. Sections on audio transcription and Braille as access routes to print information then follow. However, it is the recent developments in speech processing and speech synthesis technology that are the drivers of the wider use of audio as an information interface for visually impaired and blind people. Major sections of the chapter describe the accessible computer and the accessible Internet. Both are extremely important in the processing and provision of information and there are many interface options to make these systems accessible to visually impaired and blind people. Finally, since telecommunications is an important information channel and mobile telephony is increasingly obtaining computer and Internet capabilities, the chapter closes by reviewing accessible telecommunications technology.

The learning objectives for the chapter are:
• Understanding a taxonomy for low vision aids.
• Appreciating the assistive technologies that are used for the audio and tactile transcriptions of print materials.
• Understanding of the different input and output devices that can be used to make computer systems accessible.
• Understanding how the World Wide Web can be made accessible to visually impaired and blind people.
• Studying technologies for accessible telecommunications.

12.1 Introduction

Access to information is becoming increasingly important and the term Information Society is often used, with a particular stress on electronically transmitted information. Most of this information is obtained via the visual and auditory senses and therefore, unless it is available in alternative formats and/or appropriate technology is available to make it accessible, people with sensory impairments will be unable to access a large part of this information.

Electronic transmission by information and telecommunications technologies has become extremely important in the industrialised countries. The term digital divide has been used to describe the gap between those who do and do not have access to computer technology and the Internet in particular and it has been suggested that those on the wrong side of the digital divide will be the new havenots. Access to computer technology is generally through a graphical user interface and therefore not easily accessible to blind people.

Screen reader technology (see Section 12.6 and Chapter 13) is fairly well developed, but can only be used if documents are appropriately designed. The issues are particularly complex in the context of theWorldWideWeb with its multimedia, multimodal potential for the presentation of information using text, speech, animations, photographs, video, colour effects and sound effects.However, aswell as complicating accessibility, this multimedia potential also enables the Web to be made accessible. This requires attention to the accessibility of both web authoring tools and web content. As will be discussed in Section 12.7, guidelines for both areas have been drawn up by the WorldWideWeb Consortium (W3C)Web Accessibility Initiative."