On Silence: Part II

3. Between categories of options

In our example, the system plays to the user three possible stock-related commands to choose from, and then plays one more option for transferring to a manager. Since the fourth option is not a stock-related command, a one second pause should be inserted between the last stock command option and the announcement for the next command, "You can also say..."

SYSTEM: What would you like to do next? You can say,
[SILENCE]
"Get quotes,"
[SILENCE]
"Buy stock," or
[SILENCE]
"Sell stock."
[SILENCE]
You can also say,
[SILENCE]
"Speak to a manager."

4. When interacting with power-users

Most of the users to the stock-management application we are using for this example are going to be repeat users – that is, power-users who will not want to listen to all the menu options every time they call. In such heavy power-user applications, use silences prior to listing menu options. In this case, add a two-second pause after, "What would you like to do next?"

SYSTEM: What would you like to do next?
[SILENCE]
You can say,
[SILENCE]
"Get quotes,"
[SILENCE]
"Buy stock," or
[SILENCE]
"Sell stock."
[SILENCE]
You can also say,
[SILENCE]
"Speak to a manager."

5. After echoing

A brief echo from the system of the option selected by the user can serve as a reassuring confirmation that the system understood what the user said, or, in case of misrecognition, as a quick indication of error. In either case, insert a brief silence after the echo. In case of correct recognition, the silence will prepare the user for the next prompt, while in case of misrecognition, it will give the user an opportunity to barge-in with a correction. (Of course, you will need to configure an error strategy that can elegantly recover from such an error.)

SYSTEM: What would you like to do next?
[SILENCE]
You can say,
[SILENCE]
"Get quotes,"
[SILENCE]
"Buy stock," or
[SILENCE]
"Sell stock."
[SILENCE]
You can also say,
[SILENCE]
"Speak to a manager."

User: Get quotes.

SYSTEM: Getting quotes.
[SILENCE]
As of 10:25 am…

6. Before and after TTS prompts

As we have mentioned in a previous newsletter, avoid mixing recorded prompts with computerized, TTS prompts. Mixed prompts make for an unpleasant audio experience and should be avoided whenever possible. In cases where you have no choice but to mix human-recorded and computer-generated prompts, insert a pause between the recorded prompts and the TTS prompts. The silence will alleviate the jarring transition and will increase the level of listener comprehension.

SYSTEM: Getting quotes.
[SILENCE]
As of 10:25 am.
[SILENCE]
IBM is trading at
[SILENCE]
eighty two dollars and thirty five cents
[SILENCE]
MicroStrategy at
[SILENCE]
one hundred and three dollars and twenty four cents
[SILENCE]
and Google at
[SILENCE]
three hundred seventy four dollars and thirteen cents

Here is the entire interaction, with all silences inserted:

SYSTEM: What would you like to do next?
[SILENCE]
You can say,
[SILENCE]
"Get quotes,"
[SILENCE]
"Buy stock," or
[SILENCE]
"Sell stock."
[SILENCE]
You can also say,
[SILENCE]
"Speak to a manager."

User: Get quotes.

SYSTEM: Getting quotes.
[SILENCE]
As of 10:25 am
[SILENCE]
IBM is trading at
[SILENCE]
eighty two dollars and thirty five cents
[SILENCE]
MicroStrategy at
[SILENCE]
one hundred and three dollars and twenty four cents
[SILENCE]
and Google at
[SILENCE]
three hundred seventy four dollars and thirteen cents

On Silence: Part I

Silence is for VUI design what the number zero is for algebra. As a concept and a tool, it is at the same time essential, ubiquitous, and taken for granted. In this post, I highlight the main cases where the use of silences and pauses can contribute to a smoother, more usable VUI.

Take the following brief interaction between an IVR stock management application and a human user.

System: What would you like to do next? You can say, "Get quotes," "Buy stock,” or "Sell stock." You can also say, "Speak to a manager."

User: Get quotes.

System: Getting quotes. As of 10:25 am, IBM is trading at eighty two dollars and thirty five cents, MicroStrategy at one hundred three dollars and twenty four cents, and Google at three hundred seventy four dollars and thirteen cents.

Let's pinpoint where silences can enhance the usability of the voice interface. I will list three points in the dialog where silences are needed. I will list more in the next post.

1. Prior to listing menu options

When the system is about to provide the user with a list of options, a brief, half-second pause should be inserted between the announcement prompt and the first option that is played to the listener.

System: What would you like to do next? You can say,
[SILENCE]
"Get quotes," "Buy stock," or "Sell stock."
You can also say,
[SILENCE]
"Speak to a manager."

2. Between options in a menu list

When listing options for the user to choose from, separate consecutive options with half-second silences. The pauses will give the listener time to decide whether to select the option or wait for the next option.

System: What would you like to do next? You can say,
[SILENCE]
"Get quotes,"
[SILENCE]
"Buy stock," or
[SILENCE]
"Sell stock." You can also say,
[SILENCE]
"Speak to a manager."