.. ypertext is used with multimedia in order to produce a system in which learners can determine their own paths through the medium. Hypertext is the process of linking concepts within text documents through the use of 'hotwords'. A hotword is an active word within a document that the user can click on to navigate to another part of the project or to initiate some form of interaction. However navigation by hypertext can be confusing, it can be easy for a user to become 'lost in hyperspace'. After a few clicks users can be so far from the original topic that they become hopelessly confused.

Nearly all multimedia applications include text in some form. Text and the written language remain the most common way of communicating information in our society. The computer brings extra power to text, not only by allowing you to manipulate its size and shape but also making it an interactive medium. The ability to show moving images using digital video can greatly enhance IMM projects. Just as video has a role in multimedia, sound also plays an important part in a project.

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A few carefully placed sounds can greatly enhance a project, but a continuous monologue can be highly distracting. With the text-to-speech technology, the computer interprets text and converts it into phonetic sounds in much the same way as a human would. Thus, the computer can read back any text within any program with reasonable fidelity. This feature is very useful within an IMM program because large amounts of text can be converted to audio without large sound files. A particular use of this technology is to offer an alternative for vision-impaired people. There are however, some disadvantages to computer generated speech.

The speech can sound robotic compared to human speech and it lacks the variable information that can make human speakers appealing. Unlike print or graphics, animation is a dynamic medium. We get a sense of relative timing, position, direction and speed of action. We need no captions because the message is conveyed by the motion and the scene. Simply put, animation is the process of creating, usually graphically a series of frames and then having them display rapidly to get a sense of movement. Video provides high-speed information transfer and shows temporal relationships. Video is produced by successive capture and storage of images as they change with time.

Two types of speech are available for use by multimedia developers: digitised and synthesised. Digitised speech provides high quality natural speech while synthesised speech may not sound as natural as human speech. Even with improved techniques for generating speech, it is not incorporated into multimedia programs as often as it could be. This may be due to a lack of understanding of how high quality speech is produced. Multimedia interface designers have typically used a navigation/map metaphor, a menu/hierarchy metaphor or a journal (sequence) metaphor.

An example of the first strategy is the Virtual Museum, produced by Apple Computer. Here the user accesses the multimedia information by navigating through the virtual museum, moving from room to room by selecting directions of movement. Examples of the second strategy include on-line encyclopaedias and electronic books where a table of contents is used to organise the material. It is helpful to view multimedia applications as a convergence of today's content and titles, such as movies and books of today's computer application programs, such as word processors and of today's network services. As an example a multimedia book should have the following features.

Besides text, the book has other media that the author created, including not only text, graphics and images but also audio and video to make the book's content clearer or more enjoyable. Programs should be built-in to help a user navigate through the author's media. Multimedia's driving technologies, mainly digital electronics and fiberoptic communications are making more and more functions sufficiently economical for consumers to use. Example applications include: Desktop Video Conferences with collaboration Multimedia Store-and-Forward mail Consumer Edutainment, Infotainmnet, Sociotainment Digital Libraries Video on demand Hybrid Applications IMM has many applications in libraries. IMM can bring knowledge in its entire media formats into condensed, accessible forms capable of being used for reference and educational applications. On the whole, within the library sector IMM is currently regarded with some ambivalence.

Many library professionals look upon it as an interesting technology, but one that will require significant investment and change if its potential is to be fully realised. Possible barriers to the effective adoption of IMM by librarians may be cited as financial constraints and a lack of requisite resources resulting in a lack of opportunity to become familiar with the new and emergent systems; ingrained traditional resistance to change; a degree of uncertainty regarding the appropriateness of the technology to various applications; an inability to grasp the significance of IMM and a lack of experience, knowledge and skills in regard to IMM among library professionals. Example applications include the Book House - a library system using hypertext techniques to help users find books without the limitations of traditional information retrieval. The user interface of the Book House is based on a building like a real library with the user being able to enter rooms filled with children's books, adult books etc. The system supports four basic search strategies, using icons and pictures to enable location of the books or topic sought.

Voice response and voice recognition technologies could be used in a library situation, this could mean that merely speaking a unique book identifier or name could trigger the system into automatically filling in the remainder of the bibliographic or personal details relating to that item or person. Increasingly, multimedia systems will be developed with the aim of allowing non-textual information to be used directly, in a demonstrational manner. Even when text is present other media provide different additional information. Also, when dealing with multimedia, users are naturally disposed to interact in ways other than those developed for text. A first step to giving the user the impression that he/she is dealing directly with non-textual material allows database search on the basis of identifying images that best suit the user's purposes.

An initial query that turns up a large number of images can be refined by allowing the user to point a few images out of the set that contain items of interest. The system can then use the text descriptions attached to the chosen images to form a new query and offer a further set of possibly more relevant images. My conclusion is that design could benefit tremendously from open and collaborative multimedia research - not from relatively closed multimedia packages.