MAS.632 Conversational Computer Systems - MIT OpenCourseWare

172 VOICE (OMMURICAION WITH COMPUTERS
hardware, suitable software-based recognition requiring no additional hardware
is already becoming commercially available.'
Xspak Fondi..#ty
Xspeak provided for the use of voice for the first two mouse functions previously
mentioned: focus management and navigation among windows that may be
obscured by other windows. Xspeak worked with real-estate-driven window managers
supporting overlapped windows. Each window had a name; speaking its
name exposed the window. Xspeak then moved the cursor into the window so the
window manager assigned it the keyboard focus. Thus the user could move
among applications sending keystrokes to each in turn without removing his or
her hands from the keyboard. Additional commands allowed the user to raise or
lower the window in which the cursor currently appeared.
Xspeak employed a small window to provide both textual feedback to the user
and recognition control capabilities (see Figure 8.3). As each word was recognized,
it was displayed in this window. In ordinary use this window was ignored
as the window reconfiguration provided adequate feedback, but the display panel
was useful when recognition results were particularly poor and the user needed
to confirm operation of the recognizer. Through the control panel the user could
name a new window; this involved clicking on the window and speaking a name
that was then trained into a recognition template. The control panel also provided
a software "switch" to temporarily disable recognition when the user
wished to speak with a visitor or on the telephone. Another button brought up a
configuration window, which allowed the user to retrain the recognizer's vocabulary,
configure the audio gain of the speech recognizer, and transfer the recognition
templates to disk.
Xspeak was an application not a window manager (see Figure 8.4). It worked
by capturing recognition results and sending X protocol requests to the server. As
with any client application, these requests could be redirected through the window
manager, and the window manager received notification of the changes in
window configuration or cursor location. Because Xspeak did not replace the window
manager, it could be used across a wide range of workstation window system
environments.
Why Speech?
Xspeak was motivated by the belief that window system navigation is a task suitable
to voice and well matched to the capabilities of current speech input devices.
Using speech recognition to replace the workstation keyboard would be very difficult;
it would require large vocabulary speech recognition devices capable of
dealing with the syntaxes of both English text as well as program text and oper-
SXspeak has recently been revived using all-software recognition. This greatly facilitates
deployment of the application.