Basic Principles for Designing VUI

VUI (voice user interface) comes with a set of expectations from users. The give and take of conversation is cooperative and intuitive. Talking with VUI should be, too.

Options, but not too many

It’s helpful to give users information about what they can do. Keep them from getting lost by offering several options as a guide to completing a task. Include an exit option. And while options are helpful, too many is confusing, so keep them precise and minimal and you’ll avoid frustrating your users. This is why mapping the conversation flow is critical—good conversational design includes both flow and content, input and output. If the experience is confusing, users will get lost and frustrated. If the content is not engaging “in the right way,” users will get bored and frustrated. And just like traditional screen design, the “right way” depends on a variety of factors (user demographics, your brand, etc.).


We all know how frustrating IVR (interactive voice response) can be when there’s a long menu and you’re not sure which option to use. Think of a phone tree: “Did I want option 3 or should I wait for more options?” “How many options are there?” Thus, a knowledgeable designer will avoid long menus.


Layered design

Great VUI involves additional layers of design. If a user asks Alexa to turn off the lights, the response should be, “Sure, I’ll turn off the lights” instead of simply, “Sure.” Confirming the instruction with the response ensures the user knows the request is understood. And if the request is not understood? Failing gracefully is also important. “I’m sorry. I’m having trouble fulfilling your request” and “Would you like to hear the options?” can help users get back on the right path. These can help account for the fact that user input can vary greatly. How many ways can a user say something as simple as “yes?”


VUI is a two-way street. Designed right, it will enhance users’ understanding of your product and make them want to come back for more.


Next week: Trends in VUI