Listening

Worked exercise Suggest ideas for an interface which uses the properties of sound effectively.

Answer You might approach this exercise by considering how sound could be added to an application

with which you are familiar. Use your imagination. This is also a good subject for

a literature survey (starting with the references in Chapter 10).

Speech sounds can obviously be used to convey information. This is useful not only for

the visually impaired but also for any application where the user’s attention has to be

divided (for example, power plant control, flight control, etc.). Uses of non-speech

sounds include the following:

• Attention – to attract the user’s attention to a critical situation or to the end of a

process, for example.

• Status information – continuous background sounds can be used to convey status

information. For example, monitoring the progress of a process (without the need

for visual attention).

• Confirmation – a sound associated with an action to confirm that the action has

been carried out. For example, associating a sound with deleting a file.

• Navigation – using changing sound to indicate where the user is in a system. For

example, what about sound to support navigation in hypertext?

Worked exercise Identify the goals and operators involved in the problem ‘delete the second paragraph of the

document’ on a word processor. Now use a word processor to delete a paragraph and note

your actions, goals and subgoals. How well did they match your earlier description?

Answer Assume you have a document open and you are at some arbitrary position within it.

You also need to decide which operators are available and what their preconditions and

results are. Based on an imaginary word processor we assume the following operators

(you may wish to use your own WP package):

Operator Precondition Result

delete_paragraph Cursor at start of paragraph Paragraph deleted

move_to_paragraph Cursor anywhere in document Cursor moves to start...