Voice User Interface Design VUI

As part of an ongoing series, I thought I would share with you some of the error handling guidelines I follow when designing Voice User Interfaces. As you may have noticed, even though there are a few ‘guidelines’ out there, there isn’t a real industry consensus around when should each guideline be used, their pros and cons, or data to support a particular strategy.

So here it is, a list of what I consider the Top 5:

Guideline #1: First errors as retries - the power of intent

When an event is thrown – either by a no speech or no match event – most speech applications tend to have a single prompt that attempts to help the caller recover.
Unfortunately, both of those scenarios – a caller not responding, saying something the system wasn’t expecting, or triggering barge-in – are consequences of different intents.

From Pilot analysis we have observed that most callers tend to react positively to “retry” strategies that attempt to address both of those scenarios while at the same time avoid making it obvious to the caller than an actual error has occurred.

There are two main strategies that can be used independently or combined to implement such a strategy:

a) Repeat the same question with a different intonation.
Just as people behave naturally on their day to day interactions with someone else, we ask a question and then if the respondent stays silent, we simply repeat the same question with different rising intonation that conveys a natural repetition.
For example, if someone is going through the identification process and we were to ask “What’s your ACCOUNT number?” as an initial prompt and an error is triggered, we would repeat the same question with rising intonation that ends up a little higher than the original one (e.g. “What’s your account NUMBER??”)

b) Rephrase the question while keeping it simple and direct.
To help callers that may not have understood the question in the first place or that triggered a barge-in event earlier enough to where they couldn’t hear the question in the first place, we simply rephrase the question without adding more detail to it.
For example, if someone completes a transaction and we want to decide whether to complete the call or offer them more choices, we could ask “Is there anything else I can help you with?”, using use as a first error prompt: “Would you like to do something else?”

Other articles on this series: [2], [3], [4], [5] and [extra]

This entry was posted on Monday, February 5th, 2007 at 2:35 pm and is filed under Usability, Dialog Design. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.