Abstract
Interest in the World-Wide Web (WWW), a collection of hypermedia
information distributed across the Internet, has exploded with the
advent of Mosaic, a graphical user interface for navigating the WWW. In
spite of Mosaic's popularity, studies have found usability problems in
the original interface, especially with regard to feedback, terminology,
and adherence to GUI guidelines [2, 4]. This paper reports on a
preliminary investigation of auditory feedback as one approach to
enhancing Mosaic's user interface. The Audible Web is Mosaic embedded
with non-speech auditory cues intended to aid user monitoring of data
transfer progress, provide feedback for user actions, and to provide
content feedback to aid navigation of the WWW.
Keywords:
Auditory interface, World-Wide Web, WWW, Mosaic user interface, Mosaic,
WWW browsers.
Introduction
We chose Mosaic as a test platform for auditory enhancements because it
exhibits known HCI problems: users get little or no feedback about the
size and content of information referenced by links, time to obtain that
information, and the results of ongoing processes [2, 4]. The highly
visual task of scanning through text for links suggested to us that
Mosaic users could benefit from audio. By using audio rather than visual
enhancements, our aim was to provide more information while shifting
additional cognitive load to a different modality.
Why Use Sound?
Non-speech auditory cues can complement visual interfaces by increasing
a user's sense of engagement, enhancing monitoring of background
processes, and reinforcing visually represented information [3,
5]. These principles are familiar to anyone who has played a video game
with and without the sound effects.
In addition, there are situations when graphical information display may
be inappropriate or invasive. For ongoing processes, auditory cues can
notify users about progress, completion, and errors without distracting
them from their visual task.
Why These Sounds?
When possible, our choice of auditory cues was motivated by the existing
literature [1, 6]. Building on Gaver's auditory icon research, everyday
sounds were mapped to computer events by analogy with everyday
sound-producing events [3]. Where possible, the sound of a real world
event was chosen as an auditory cue (e.g., typewriter for a text
file). The sounds that are not "realistic" were selected based on their
subjective affordance (e.g., low heavy piano note for large files). All
of the sounds used in The Audible Web are presented at low levels above
background noise in an effort to inform rather than distract users.
ENHANCEMENTS PROVIDED BY SOUND
The Audible Web uses auditory cues to enhance the interaction between
users and Mosaic in three ways: by aiding users' monitoring of data
transfer in progress, by providing feedback for user actions, and by
providing content feedback to aid navigation.
Monitor Data Transfer Progress
After users click on a hypermedia link in Mosaic, the globe icon spins
and a series of technical messages are displayed at the bottom of the
window. Not only are these cues obscure, they are of little use if a
user's visual attention is focused elsewhere or Mosaic is iconified.
Because sound is particularly useful for monitoring time-varying
processes [3, 5], The Audible Web provides auditory cues which provide
progress feedback for normal data transfer, opening of external
programs, and errors. While data transfer is progressing normally, users
hear clicks and pops. A sliding sound indicates when an external program
is opened. If there is a error, users hear the sound of breaking
glass.
Figure 1. No caption.
Feedback for User Actions
Ede and Roshak [2] found that many Mosaic users were unsure if menu
items they selected had performed the requested action. The Audible Web
provides feedback to reinforce user actions via auditory cues for button
presses, menu selections, scroll bar movements, and link selections. The
aim of this auditory feedback is to confirm actions without interrupting
visual scanning and to heighten user engagement with The Audible Web by
making sound an expected part of the interaction.
Figure 2. No caption.
Aid Navigation through Content Feedback
Whether a hypermedia link points to an image, another document, an audio
clip, or to nowhere, every text-labeled link looks the same in
Mosaic. Having little information about a link, users can only activate
it and ponder the questions, "What information will I get?" and "How
long will this take?".
Using non-speech audio, The Audible Web provides feedback about the
probable type of information at the other end of a link before the link
is activated. As users move the pointer over each link, a different
audio cue plays to indicate various file types (See the table
below). The aim of this feedback is to help users quickly decide if
links point to information of interest to them.
By pressing the right mouse button when the pointer is over a link,
users get auditory feedback for proportional transfer time, file type,
file size, and errors. The length of time a tick-tock of a clock is
played indicates the proportional data transfer time, an auditory cue
indicates the file type, and a piano note conveys the size of the file
(by varying pitch with file size). If the server is down or the file is
not found, the user hears the sound of breaking glass.
For example, suppose that a user in New York queries a link that points
to a small text file in London. The user hears a few seconds of the
tick-tock sound (indicating proportional data transfer time) followed by
the sound of a typewriter (indicating a text file) and a high piano note
(indicating a small file).
Figure 3. No caption.
CONCLUSION
The Audible Web is a prototype that adds auditory cues to Mosaic to aid
user monitoring of data transfer in progress, provide feedback for user
actions, and provide content feedback to aid navigation of the WWW.
Our informal evaluation of The Audible Web suggests that audio has
special value for informing users without distracting them from a
primarily visual task. It becomes possible, for example, to query a
link, but to go on reading while simultaneously learning more about the
size, availability, type, and content pointed to by the link.
As users of The Audible Web, we find that the constant low level audio
feedback for user actions as well as link events and attributes creates
a ubiquitous audio environment, in which sounds are an expected part of
interactions rather than a surprise or salient special event. This
preliminary experience suggests further study is needed to understand
how human-computer interactions are affected by environments in which
audio is truly ubiquitous.
Naturally, there are many purposes for which audio is not well
suited. Users can acquire an abstract sense of file size from audio
cues, for example, but if they need to know that one file is 1.2
megabytes while another is 1.4 megabytes, non-speech audio may not
provide the information they need. More work is needed to determine when
and where audio is an appropriate interface element.
The Audible Web prototype suggests a host of research questions about
the use of audio in applications. In future research, we must validate
users' understanding of auditory cues, study the effectiveness of audio
for enhancing user-interface interactions, and determine users
acceptance of audio cues.
Acknowledgments
We would like to thank the members of HCI, COCO, and other groups at
SunSoft for their help and support during Mike's summer internship.
References
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