CATERING FOR THE DISABLED SURFER: A CASE STUDY IN WEB SITE NAVIGATION FOR THE DISABLED
ABSTRACT
Speech recognition can give people with severe disabilities more control over their personal environments. For people with physical disabilities affecting the use of their hands, productivity is far more personal. Speech recognition can enable some people to perform daily living tasks without assistance. For others, such as the growing number of professionals afflicted with repetitive stress syndrome (RSI), speech recognition represents a means of getting or keeping employment. Thus speech recognition as a navigation aid is a key in solving the dilemma of a subset of disabled surfers. This paper discusses the results obtained from evaluation of a website for the disabled. The results of the evaluation by local health board officials indicated a positive response to the Voice Navigable website and aided recommendations for future work such as adding a range of vocal speeds, accents and characters.
INTRODUCTION
Reasons that people with a disability use voice recognition include limited use of hands, difficulty with spelling, inability to touch type and need a fast way of working. Therefore a user needing to work “hands-free” will need a reliable method of controlling menus; a means of moving and clicking the mouse using voice commands and a correction mechanism that works completely by voice. Users with spelling difficulties need predictive correction, text to speech feature to help with proof-reading and a facility to “play back” what was dictated (i.e. your voice) and people who wish to speed up tying are likely to be most interested in speed of recognition and easy correction using the mouse. Many visually impaired users are attracted to the idea of operating their computer by voice, either necessitated through keyboarding difficulties or lack of touch-typing proficiency.
WEB ENABLED SPEECH NAVIGATION
In order to demonstrate Web site navigation via voice, a disability Web site was developed enabling voice interaction with the site. The technology selected was Interactive Speech Technology’s 1 Voice Navigation Module. MakeWord was used to vocally activate HTML pages, interface development, installing the Voice Navigation module, creating voice commands, human factors of command and control and utilising pre-recorded audio files. The site was named disABILITY Interactive consisting pages which are vocally linked and therefore navigable by speech. Interactive Speech Technologies provides a basis for incorporating voice navigation technology to Macromedia Flash movies, 3D animations and regular HTML pages. Along with MakeWord, the voice navigation module enabled voice commands throughout the Web site. Ergonomics and navigability are important issues when designing Web sites. Voice navigation answers web-surfers needs in terms of interactivity and conviviality. When a visitor of the website arrives on the page his/her browser downloads the text and pictures of that page. At the same time, the voice-navigation plugin automatically downloads the .IAS file and then waits until the user pronounces one of the vocal links contained in this .IAS file. When this happens, the plugin asks the browser to ‘jump’ to the desired page.
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The voice navigation system is based on an acoustic comparison between, on one hand, the voice link pronounced by the visitor when visiting a given page and, on the other hand, the possible voice commands available on this page. These possible voice commands are defined and recorded by the website designer. Many people who use command-and-control applications view speech recognition as a facet of the machine they are operating. For them, the role of speech is to translate verbal commands directly into action. There is often little tolerance of error and no patience for slow throughput or efficiency. Command-and-control systems must be simple and easy to use and must possess vocabulary that is easy to remember and access. Environment control systems for people with disabilities require tailoring to the needs of each individual. For people with severe speech problems this may require careful selection of vocabulary to enhance word differentiation within capabilities of the individual. Pre-recorded audio files enable the user to hear an introduction to the Web site, information about other disability groups and so forth. It adds value by way of developing interactivity between the user and the Web site.
EVALUATION
In our initial prototype, we believed that the commands were chosen and recorded with great care to guarantee a unique Voice Navigation experience to all visitors however the experience in the field was somewhat different. Over a period of two weeks of use in the community at various nursing homes, hospitals, senior citizen groups – our findings were as follows:
- Commands were chosen that were ambiguous. We simply didn’t make some of the commands different enough. The group of voice commands should not contain words that are too close together. The choice of words afterwards was always checked with MakeWord’s tester.
- Long commands were preferred. We found that commands of two or three words were preferred to shorter one word commands.
- Opposite Sex Voice Commands. We found that male voice commands had a higher miss ration than female voices. We discovered that this was due to the fact that all commands had been input by a female. When commands were mirrored by a male voice input, the miss ratio diminished. We believe that additional voices would be useful for sites aimed at children.
- Noise Control. Some of our early commands did not perform quite as good as later commands. We believe this was due to background noise in the busy undergraduate laboratory that was used for recording. Later version of the site had voice commands being recorded in a quieter environment, with a good-quality microphone and sound-card. The recording of the command was always checked just after recording it to eradicate any interference. MakeWord’s integrated voice-commands tester ensures that the voice commands that have been chosen and recorded are distinct enough. The score 0.20 is the criteria to decide whether or not the recogniser is sure. A score above a threshold of 0.20 ensures that a word is recognisable.
In addition, during the iterative testing and evaluation, a number of issues arose such as restrictions in the actual range of voices and lack of support for speech impediments. Therefore, our main priority in the near future is to:
- incorporate voices that have accents, different speeds and different tones;
- lateral development with Microsoft’s Speech Application Tags; and
- future development of ‘hands busy/eyes busy’ environment scenario
CONCLUSION
What makes interactive speech systems particularly interesting at the present time is that they have recently become commercially available in their most versatile and natural form, i.e. real-time systems that understand speaker-independent continuous speech. Acceptable-quality speech synthesis in several languages has already been in existence for some time. Our system provides a facility that enables users with different forms of disability to navigate the World Wide Web in a variety of ways. It demonstrates that the concept of Voice Navigation through the World Wide Web holds much potential for computer users with disabilities, office staff and developing the mobile Information Technology Market.
