MAS.632 Conversational Computer Systems - MIT OpenCourseWare

104 VOICE COMMUNICATION WITH (OMPUTERS
ADVANTAGES OF VOICE
everyone can hear the announcements regardless of the focus of their visual
attention. Voice can be similarly used to alert the computer user in an office when
the user requires mobility or is not paying attention to the screen.
Given these significant liabilities of voice, what advantages could possibly justify
its use? Chapter 4 suggested several roles ofvoice in conjunction with text in the
context of document-oriented applications. Voice is richer than text and more
expressive of information that may be tentative or subject to multiple interpretations.
Voice is useful for annotation because it acts as an added dimension for
placing comments on an otherwise two-dimensional view of a document page. The
rest of this section describes assets ofvoice beyond document-oriented uses.
For many styles of application discussed in this chapter, the main advantage
of speech is its accessibility via telephone-based interfaces. Telephone-based
applications can be used from nearly any telephone. Most public telephones in the
U.S. and Canada are equipped with touch tone keypads, but this is not true in
some other parts of the world, notably some European countries. When touch
tones are not available, speech recognition must be employed; unfortunately,
speech recognition over the telephone is much more error prone than touch tone
decoding.
The accessibility advantage of voice also applies to the authoring or creation of
information. The ability to capture speech as a recording for subsequent playback
allows data to be entered into a system when no other means ofinputis available,
such as recording notes on a pocket tape recorder, dictation, or leaving messages
to oneself on one's answering machine. Telephones allow callers to record information
at a distance; for example, Resnick describes a community bulletin board
enabling callers to browse as well as enter events in a public events database
by recording them [Resnick 19 9 2a]. Voice mail allows subscribers to record
messages, and Chapter 12 describes telephone access to desktop computer applications
that allow a user to record voice entries in a personal calendar. Telephonebased
recording also can be used for functions such as order entry by filling out
an audio "form" for later transcription.
Although the previous section describes the broadcast nature of speech as a
liability, in other circumstances it is an asset. The ability to reach a number oflisteners
simultaneously over a broad area, such as airport flight departure
announcements, simply could not be provided by visual displays.' Because our
ears are much less directional than our eyes, auditory cues can be delivered with
more confidence that the intended audience will be more able to be attentive at
the moment of presentation. Voice output is effective when the user is mobile or
"Itshould be noted that displays clearly are of value. Imagine having to locate your
departure gate by listening to a continuous recitation of all flights departing within the
next hour!