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."