HUMAN-COMPUTER INTERACTION SECOND EDITION
Dix, Finlay, Abowd and Beale

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Chapter 15 Out of the glass box 15.4 Non-speech sound Page 562

We have previously discussed the role of speech in the interface, but non-speech sounds offer a number of inherent advantages. Speech is serial and we have to listen to most of a sentence before we can extract the meaning; since many words make up a message this can take a relatively long period of time. On the other hand, non-speech sounds can be associated with a particular action and assimilated in a much shorter period. Non-speech sounds can also be universal; in much the same way as visual icons have the same meaning in many different countries, so can non-speech sounds. The same is not true of speech, which requires that we understand and interpret it and so have to know the language used. Non-speech sound is also able to make use of the phenomenon of auditory adaptation, in which sounds that are unchanging can fade into the background, only becoming evident when they alter or cease. One problem is that non-speech sounds have to be learned, whereas the meaning of a spoken message is obvious (at least to a user conversant in the language used). However, since users are able to learn the visual icons associated with things, this should not be seen as too great a disadvantage.

Chapter 15 Out of the glass box 15.4 Non-speech sound Page 563

Sound can be used to provide a second representation of actions and objects in the interface to support the visual mode and provide confirmation for the user. It can be used for navigation round a system, either giving redundant supporting information to the sighted user or providing the primary source of information for the visually impaired. Experiments on auditory navigation [196] have demonstrated that purely auditory clues are adequate for a user to locate up to eight targets on a screen with reasonable speed and accuracy, so there is no excuse for ignoring the role of sound in interfaces on the grounds that it may be too vague or inaccurate.

Chapter 15 Out of the glass box 15.4 Non-speech sound Page 563

Soundtrack is an early example of a word processor with an auditory interface, designed for visually disabled users [76]. The visual items in the display have been given auditory analogs, made up of tones, with synthesized speech also being used. A two-row grid of four columns is Soundtrack's main screen (see Figure 15.3); each cell makes a different tone when the cursor is in it, and by using these tones the user can navigate around the system. The tones increase in pitch from left to right, while the two rows have different timbres. Clicking on a cell makes it speak its name, giving precise information that can reorient a user who is lost or confused. Double clicking on a cell reveals a submenu of items associated with the main screen item. Items in the submenu also have tones; moving down the menu causes the tone to fall whilst moving up makes it rise. A single click causes the cell to speak its name, as before, whilst double clicking executes the associated action. Soundtrack allows text entry by speaking the words or characters as they are entered, with the user having control over the degree of feedback provided. It was found that users tended to count the different tones in order to locate their position on the screen, rather than just listen to the tones themselves, though one user with musical training did use the pitch. Soundtrack provides an auditory solution to representing a visually based word processor, though the results are not extensible to visual interfaces in general. However, it does show that the human auditory system is capable of coping with the demands of highly interactive systems, and that the notion of auditory interfaces is a reasonable one.

Chapter 15 Out of the glass box 15.4.1 Auditory icons Page 564

Auditory icons [93] use natural sounds to represent different types of objects and actions in the interface. The SonicFinder [94] for the Macintosh was developed from these ideas. It is intended as an aid for sighted users, providing support through redundancy. Natural sounds are used since people recognize, not timbre and pitch, but the source of a sound and its behaviour [250]. They will recognize a particular noise as glass breaking or a hollow pipe being tapped; a solid pipe will give a different noise indicating not only the source but also the behaviour of the sound under different conditions. In the SonicFinder, auditory icons are used to represent desktop objects and actions. So, for example, a folder is represented by a papery noise, and throwing something in the wastebasket by the sound of smashing. This helps the user to learn the sounds since they suggest familiar actions from everyday life. However, this advantage also creates a problem for auditory icons. Some objects and actions do not have obvious, naturally occurring sounds that identify them. In these cases a sound effect can be created to suggest the action or object but this moves away from the ideal of using familiar everyday sounds that require little learning. Copying has no immediate analogous sound; in the SonicFinder it is indicated by the sound of pouring a liquid into a receptacle, with the pitch rising to indicate the progress of the copying. These non-speech sounds can convey vast amounts of meaning very economically; a file arrives in a mailbox, and being a large file it makes a weighty sound. If it is a text file it makes a rustling noise, whereas a compiled program may make a metallic clang. The sound can be muffled or clear, indicating whether the mailbox is hidden by other windows or not, while the direction of the sound would indicate the position on the screen. If the sound then echoes, as it would in a large, empty room, the system load is low. All this information can be presented in a second or so.

Chapter 15 Out of the glass box 15.4.2 Earcons Page 566

An alternative to using natural sounds is to devise synthetic sounds. Earcons [25] use structured combinations of notes, called motives, to represent actions and objects (see Figure 15.4). These vary according to rhythm, pitch, timbre, scale and volume. There are two types of combination of earcon. Compound earcons combine different motives to build up a specific action, for example combining the motives for 'create' and 'file'. Family earcons represent compound earcons of similar types. As an example, operating system errors and syntax errors would be in the 'error' family. In this way, earcons can be hierarchically structured to represent menus. Earcons are easily grouped and refined owing to their compositional and hierarchical nature, but they may be harder to associate with a specific task in the interface since there is an arbitrary mapping. Conversely, auditory icons have a semantic relationship with the function that they represent, but can suffer from there being no appropriate sound for some actions.

Chapter 15 Out of the glass box 15.8 Ubiquitous computing applications research Page 570

We first introduced the notion of ubiquitous computing in Chapter 4. The interest in ubiquitous computing has surged over the past few years, thanks to some influential writings and plenty of experimental work. The defining characteristic of ubiquitous computing is the attempt to break away from the traditional desktop interaction paradigm and move computational power into the environment that surrounds the user. Rather than force the user to search out and find the computer's interface, ubiquitous computing suggests that the interface itself can take on the responsibility of locating and serving the user.

Chapter 15 Out of the glass box Background Page 571

There has been a good deal of research related to this general capture, integration, and access theme, particularly for meeting room environments and personal note taking. Work at Xerox PARC has resulted in a suite of tools to support a scribe at a meeting [159, 164], as well as some electronic whiteboard technology - the LiveBoard [81] - to support group discussion. The Marquee note-taking system from PARC [254] and the Filochat prototype at Hewlett-Packard Labs [260] both supported individual annotation. A simple pen-based interface produced automatic indexes into either a video (for Marquee) or an audio (for Filochat) stream that could be traversed later on during access and review. Stifelman used an even more natural interface of pen and paper to produce a stenographer's notepad that automatically indexed each penstroke to a digital audio record [229]. The implicit connection between the note-taking device and alternate information streams (audio and/or video) is a common theme that has also been explored at MIT's Media Lab [113] and at Apple [60].

Chapter 15 Out of the glass box Background Page 571

In all of these cases, the emphasis on ubiquity is clearly seen in the capture and integration phases. Electronic capture is moved away from traditional devices like the keyboard and brought closer to the user in the form of pen-based interfaces or actual pen and paper. There is not so much emphasis on ubiquity of access, mainly because the focus is on supporting a small group of users, usually only one. We can look at another application domain for capture, integration and access that emphasizes group access. That application domain is education, and is the concern of the Classroom 2000 project at the GVU Center at Georgia Tech [4]. One way to view classroom teaching and learning is as a group multimedia authoring activity. Before class, teachers prepare outlines, slides, or notes and students read textbooks or other assigned readings. During the lecture, the words and actions of the teacher and students expound and clarify the lessons underlying the prepared materials. It is common practice to annotate the prepared material during the lecture and to create new material as notes on a whiteboard or in a student notebook. These different forms of material - printed, written and spoken - are all related to the learning experience that defines a particular course, and yet there are virtually no facilities provided automatically to record and preserve the relationships between them. Applying a variety of ubiquitous computing technologies - electronic whiteboards, personal pen-based interfaces, digital audio and video recording, and the World Wide Web - would allow us to test whether ubiquitous computing positively affects the teaching and learning experience.

Chapter 15 Out of the glass box Defining the problem Page 574

The desktop paradigm leaves it to the user to find the interface to a computational service (such as an email browser or a calendar manager) when it is needed. A ubiquitous software service, on the other hand, finds the user. Two important characteristics of such a service are: its availability on any device handy to the user; and its adaptability to a changing set of services that the user wants. The former characteristic is referred to as the scaleable interface problem. The creation of an architecture-neutral virtual machine, such as the Java Virtual Machine, solves part of the scaleable interface problem because it now becomes possible to execute the same program on many different devices.

Chapter 15 Out of the glass box Defining the problem Page 574

There is work in the user interface development community to remove both the programmer burden and the user inflexibility of integrated software suites. Work at Georgia Tech (the CyberDesk project [5, 63]), Apple (Data Detectors [12]) and Intel (Pandit and Kalbag's Selection Recognition Agent [189]) all show the beginnings of providing automatic integration of separate computer applications based on what information the user is currently interacting with on the graphical display.

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