A number of studies have shown how audio contributes to the
human-computer interaction process to provide a richer, more robust
environment than with mere graphic feedback. Auditory feedback can
present further information when the bandwidth of graphic information
has been exhausted, as is often the case with the present emphasis on
graphic presentation. By expanding conventional interfaces in another
dimension, sounds make tasks easier and more productive. Other studies
have even shown certain types of information to be represented better
by sound than through graphics or text. Additionally, audio feedback
may complement graphics and text to create valuable redundancy,
reinforcing or reconfirming a concept in the user's mind.
For example, it seems reasonable to assume that the sounds used to
represent a particular event will be a factor in whether that event is effective or not. As pointed out above, one criteria for selection of sounds
could be consistency with the physical world. We could start by making
the sound of an on-screen button consistent its function.
As each type of
switch in real-life has its own texture and resistance, each type of
software switch (e.g. an on-screen button) could have its own sound which the user would associate with that button and that function. As familiarity with the sound
grows, the user will associate a sound not only with its respective
button, but also with its function. So not only will the user
know by the auditory cue their action was registered, they will
also know, with utter immediacy, what action was performed - without having to
read a label or other description within a dialog box. Graphics and
text could then be used to provide other information, thereby widening
the effective bandwidth of conveyed information.
Many systems use robust audio feedback with great success. The
telephone is a very general example that uses audio feedback
exclusively. Perhaps the most intense interactive systems in general
use are for playing video games. Fast-action video games use audio feedback extensively to aid in rapid interaction.
It has been shown that performance in such applications drops when the
audio feedback is removed. Perhaps a user could wield a
business or scientific application with greater speed and ease of use
with audio feedback. In doing so, the productive process might become
more enjoyable as well.
Audio also promises to bridge the gap between sight-impaired users and
graphic user interfaces (GUIs). It is ironic that the desktop/windows
systems on personal computers have enable so many persons to become
computer literate and yet have abandoned the blind, who in the past
have been productive using text-based interfaces and refreshable
Braille modules. Various groups, the Mercator
Project at the Georgia Institute of Technology and the GUIB project
funded by the European Community, are working on audible complements
for the desktop metaphor. Emphasis has been placed on determining the
best sound to correspond with each action, finding sounds which work
effectively in combination, and developing a system of localization so
that sounds are correctly associated with their respective graphic
object. Yet, as Braille is not a literal physical representation of
characters, perhaps a metaphor for the blind should not be a literal
representation either. Menus and windows are not objects which the
blind relate to, so why try to make their use audible? The blind do
have a rich auditory experience that could provide for a unique
metaphorical environment.
Considering the popularity of the World Wide Web, some of the most
important work having to do with auditory displays with respect to the
Internet is Albers' and Bergman's "The
Audible Web: Auditory Enhancements for Mosaic". Multimedia and
hypertext systems provide more information at a faster pace, requiring
more user participation to control the information flow. Because an
abundance of information arrives in the visual mode, feedback in the form
of audio might ease this process:
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. 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.
As a result of modifying Mosaic, the researchers found that audio
feedback helpfully and unobtrusively complemented the primarily visual
task of navigating the World Wide Web. They expect further research to
reveal which types of audio cues are better suited for each event and
deemed acceptable by the user.