MAS.632 Conversational Computer Systems - MIT OpenCourseWare

CASE STUDIES
Diredoan Assistme
Inte•o•cle Resp
cess of entering the next digit(s) anyway so the system must quickly determine
whether the additional input is a continuation of the spelling or the next step in
the user interaction. One technique reported in [Gould et al. 19871 is to "absorb"
this further input as long as it conforms to the remaining digits in the selected
item.
Another shortcut for selecting alphabetic choices by spelling is user-initiated
completion. A special key is used to jump from spelling input to a menu style
selection. For example, to continue with the name database example, the user
could type "3*" and get "Davis," which is unique. But entering "7*"or even "76*"
would invoke a menu to select between "Smith" and "South." With user-initiated
completion, the user gets to choose between pressing more digits in trade for a
shorter menu, but with a large database it may not be intuitive how many names
will match a sequence of a few digits.
This section describes three voice response applications that illustrate application
of the design considerations and interaction techniques just mentioned.
Three different systems all employing speech synthesis for output are discussed.
Both the first and third examples are telephone-based information retrieval systems,
one for receiving driving directions and the other for reading electronic
mail. The remaining system also gives driving directions but operates in real
time in an automobile.
Direction Assistance [Davis and Trobaugh 19871 is a program that gives driving
directions over the telephone. 7 It is an example of the usefulness of speech synthesis
in situations where recorded speech would be much more difficult to
employ for two reasons. First, Direction Assistance generates fairly complicated
textual descriptions of an abstracted data structure, i.e., a route traversing links
in a street database. Second, the database of street names is large enough that
preparing a recording of each would be tedious. The database does accommodate
phonetic spellings for those street names that the synthesizer mispronounces.
To use Direction Assistance, a user calls and enters both source and destination
addresses with touch tones. The system then determines a route between these
two points and translates the route into a textual description to be read by the
speech synthesizer. The motivation for a telephone-based interface is to make
this service available while driving around a city and, in particular, when one is
'Direction Assistance was written by Jim Davis and Thomas Trobaugh initially at
Thinking Machines, Inc., and later at the MIT Media Lab. Davis also used it as a basis for
work in intonation at AT&T Bell Laboratories IDavis and Hirschberg 19881].
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