1. Field of the Invention
The present invention relates generally to a voice-activated navigation means and method for hypertext documents.
2. Description of the Related Art
Hypertext systems are rapidly gaining increasing significance in many areas of data and communications technology. The important examples that have already been realized are:                Typical hypertext help systems and hypertext documentation for software applications (for example, under graphics operating systems for personal computers), wherein the user can usually navigate within single hypertext documents that are stored as data files on a single computer, as well as        the World Wide Web (WWW), a worldwide hypertext network based on the Internet that makes it possible for the user to navigate through a plurality of hypertext documents linked to one another that cite one another (i.e., reference one another) and that are generally stored on a great number of computers in the network at a great distance from one another. Hypertext documents thereby generally contain information in the form of text, digital images or audio or video data or combinations thereof.        
A significant, characteristic feature of all hypertext systems is the possibility of navigation. In addition to containing the actual text of the document, a hypertext document contains special character sequences that can also be a component part of the actual text and that are usually referred to as links or hyper-links and that serve the purpose of hypertext navigation. Normally, these character sequences are specially marked, for example by being displayed in a different color or are emphasized in some other way, to distinguish the special character sequences from the ordinary text of the document. When a user of a hypertext system selects such a link, usually with a short click with the mouse or other pointing device, the hypertext system reacts to this instruction in that it displays the part of the same hypertext document associate with this character sequence (or link) or the system displays a different hypertext document. Other possible reactions to the selection of the link are opening up a connection to a different computer, for example to an on line data bank, starting another application program, opening another data file, initiating a data processing process or a combination of such possible reactions.
In addition thereto, hypertext systems usually also execute other instructions that are not associated with the character sequences (links) in the hypertext documents such as, for example, paging through documents that are already displayed or through document parts (for example, pages of the document), storing hypertext pages in what are referred to as hot lists, retrieving or paging through pages stored in hot lists, reloading images, etc. These instructions are normally input in the way typical for graphic user interfaces, for example with the mouse or other pointed device.
There are a number of possible applications of hypertext-based systems wherein the traditional way of inputting instructions or of activating links is considered to be disturbing, undesirable or even impossible. This, for example, is the case when the user is impeded, his hands are busy with managing other jobs or when the ambient conditions forbid the employment of traditional input devices. Voice recognition is available here as a simple, natural type of input that assumes less expertise on the part of the user than other input means.
The integration of traditional, acoustic voice recognition systems, i.e. systems for recognizing spoken language, with hypertext systems, which are also known as “viewer” or “browser” systems, are opposed by technological difficulties. The voice recognition system, namely, must be in the position to recognize every word that can occur as a link in a hypertext document. Because practically every word in the text can also be a hyper-link, extremely large dictionaries would be required for this purpose, and these large dictionaries would reduce the processing speed and the recognition performance of this system to an unjustifiable extent. Even if the employment of 2 extremely large dictionaries were possible, the numerous coining of new words and proper names could not be recognized, these new words being so typical of many hypertext applications, specifically, however, for hypertext networks such as the World Wide Web. Probably for this reason, a hypertext navigation system to be controlled by voice recognition has not yet been disclosed.