The introductory message(s) that the user hears when starting the
application can be very important. In general, introductions should
contain the following information:
- Welcome
- Purpose (optional)
- Global List (only two or three
key commands)
- Speak After Tone (if using
turn-taking tones)
- Initial Prompt
Welcome
The welcome prompt
should be short and simple, but also make clear that the user is talking
to a machine, not a person. For example:
| System: |
Welcome to the automated currency conversion
system. |
|
To speed up the interaction for expert users, you might
want to provide a brief (for example, 1.5 second) recognition window
without a tone after this welcome prompt. Expert users will know how
to provide valid input; if a silence timeout occurs, you can presume
that the user is a novice and proceed to play the remaining introductory
prompts. Keep in mind, however, that if the application allows barge-in,
the system needs about 3-5 seconds to set it up. For this reason,
you should plan to suppress barge-in and play 3-5 seconds (12-20 syllables)
of speech in the welcome message before pausing to invite the caller
to barge in. It is very important to trim all silence from the end
of the audio that plays while the system is setting up barge-in (specifically,
calibrating echo cancellation). If you need a pause between the end
of this audio file and the beginning of the next, put the pause at
the beginning of the next audio file, which begins playing when the
application enables barge-in. Otherwise, the silence at the end of
the initial audio will invite users to barge-in, but will cause usability
problems because the application has not yet enabled barge-in.
Note: A
similar strategy with much shorter (say, 0.75 second) recognition
windows can be used at other logical pausing places during and between
prompts, such as at the end of a sentence or after each menu item.
These brief pauses will give users the opportunity to talk without
feeling that they are “being rude” by interrupting the application.
Purpose
If necessary, state
the purpose of the system. For example:
| System: |
This system provides exchange rates between American dollars and the
major currencies of the world.
|
|
Note: You may not need to include a statement of purpose
if the welcome prompt adequately conveys the system's purpose. Don't
include a statement of purpose unless it's necessary; it makes the
introduction longer.
Global list
Next, you will
probably want to tell the user what commands are always available.
If you have a large global set of commands, you probably don't want
to list all of them here – just the key ones. For example:
| System: |
The commands “Repeat” and “Start over”
are always available. |
|
Speak after tone
In general,
applications in which barge-in has been disabled should use a tone
to signal the user to speak. In such cases, you should include a prompt
such as:
| System: |
Speak to the system after the tone. |
|
Interrupt any time
If you
enable barge-in, you might want to let the caller know that it's OK
to interrupt the application. It's not absolutely necessary because
most users will naturally interrupt the application when it pauses.
For some users, however, it might be beneficial to mention this explicitly.
For example:
| System: |
You can interrupt me at any time. When
you hear the choice you want, just say it. |
|
Initial prompt
Finally, present
the user with the first prompt requiring user input. For example:
| System: |
Select Buy Currency or Sell Currency. |
|