Humans embody the physiology needed to absorb information in the
form of sound. Just as the eye can perceive many different variations of light -
hue, briteness, contrast - the ear is capable of sensing a vast array of sounds
through the alteration of timbre, loudness, and pitch. The mind can then
associate these sounds with events, objects, or abstract ideas. Most commonly,
sound-as-information exists as speech or music, and indeed this will continue
on the Internet. Audio content is also commonly generated by machines to relay
information, and this use will also continue on the Internet
Examples: In a hospital, the familar sound of the electrocardiograph
(ECG) beeps in rhythm to the heart; a woman's pager alerts her on a street
corner; the telegraph emits evenly-spaced clicks in Morse code. All these are
examples of auditory displays, sounds made by a machine in order to relate
information. In an age when language has become the predominant form of
communication, sound plays an important role in our lives.
There are instances when language is too complicated to demonstrate
relations among events, so a graph may be used. A company's logo
immediately communicates the idea of an entire organization and it's
products or services. Likewise, combonations of sounds, varying by timbre,
pitch, or time, can show relations among events, as with the
electrocardiograph. Particular timbres arrive in the mind with unavoidable
associations, as with the whine of an ambulance siren.
In other instances, there is a high density of perceptual material that
must be perceived, and various combinations must be used. For a project at
NASA, an array of video and audio displays were needed to control the flight
path of satellites. All necessary communication took place
within a 10 minute window as each satellite passed overhead a ground
station. With such a short time span, visual displays alone did not convey
enough information and necessitated the collaborative use of audio signals.