1.6.6 Problems with the use of sound
Pre-recorded digitised speech can be included in a UI relatively easily, but generating speech is harder. One of the methods for synthesising speech is called concatenation. The idea behind concatenation is that the computer stores sentences, phrases or word segments of real human speech. New sentences are constructed by arranging words in the right order. For example, with current telephone directory enquiry systems in many countries, after having made an enquiry of a human operator, a voice says something like: ‘the number you require is 273148’. The phrase ‘the number you require is’ is smooth and flowing (having been recorded in full by a human speaker). The number itself is rather jerky and stilted, as digital recordings of the individual digits are played back one after another.
Unlike the other media that we have considered, sound has the potential to intrude upon the environment. This can be overcome with the use of headphones, but not all users choose to use headphones and they are inadvisable in some hazardous environments. It is often a good principle to allow users to change the volume, switching it off altogether if necessary.
Sound is not good at conveying detailed information, such as describing events, unless accompanied by video or still images, and it is often difficult to remember precisely. To maximise its effects, it is often best to combine sound with other media.
Imagine that you are designing a multimedia information kiosk for a leisure centre. The kiosk is intended to give information about the different facilities that are available, and to provide lists of times and prices. Give two different ways in which you could use each of the following media: video clips, animation, images and sound. Explain the advantages of each.
Video clips. A talking head of the manager could be used to welcome users to the leisure centre. This would (hopefully) inspire them to use the facilities. Short clips could also be shown of the swimming baths, gymnasium and other facilities. These would give a real sense of what the facilities are like.
Animation. Animation could be used to attract the attention of passers by — there could be a rolling animation that shows that the system is operating. Many of the users will be using the kiosk for the first time, so it may be helpful to have animations, indicating what to do. Thus a button that must be pressed in order to proceed may have an arrow that repeatedly moves towards it.
Images. Photographs of staff members could be used, as could illustrations of the facilities. These would help the leisure centre to seem more attractive and friendly.
Sound. Music could be used in combination with the animation intended to attract passers by. Recordings from the different facilities could also be used. For example, the description of the swimming pool could be accompanied by sounds recorded by the pool. This could make the pool sound a happy and interesting place to be.