Many user experience professionals think about their work in the physical or digital space, usually in the form of a visual design or layout. Increasingly, though, UX professionals are working in a new, less tangible realm: audio.

In fact, consumer research group Juniper found that more than 3 billion voice assistants were active worldwide in 2019, with an estimated 8 billion to be active by 2023. This means if you haven’t already worked with audio interfaces as a UX professional, you likely will soon.

To help, we’ve put together 4 tips for designing an effective voice user interface.

Consider when audio only is appropriate. Humans learn and absorb information in many different ways. Some of us are visual learners, while others learn best by listening or by practicing with our hands. When designing an audio interface, think about the types of exchanges that will work best in audio form. Some tasks, such as setting an alarm or answering a quick trivia question, could be done in audio only. Others, such as providing driving directions or more complex, multi-step information, might be best done through a combination of audio and visuals on a mobile device or computer. 

Understand the limitations of audio interfaces. We live in an era where it’s entirely possible to ask our phones to carry out complex actions with solely the power of our voice. But as powerful as they may be, voice assistant technology still has blind spots and shortcomings. For example, conversations that require voice assistants to “remember” earlier references in a sentence or understand slang terms will probably fall short. When designing a voice user interface, it’s important to consider not only what the voice technology can do but also its current limitations. 

Apply UX design principles to speech. When you’re designing a UX user flow for an app or website, you make sure that the user flow makes very clear to a potential user which actions are available to them and what those actions do. When designing a voice user interface, those same “signposts” are also necessary. For example, if you are designing an exchange in which a voice assistant asks the user if they would like to take a particular action, it’s very important to keep the language clear and understandable. A question like, “Do you want to set an alarm for your next meeting?” is clear enough, but a question like, “Do you want to set an alarm for your 3 pm meeting?” is stronger because it is more specific and targeted. 

Think about the different branches a conversation could take. Talking to our family and friends is a very different experience than talking with a digital interface (at least for now). In human speech, our conversations constantly ebb and flow, moving in different directions and referencing topics that came up earlier in the chat. Those types of conversations just aren’t practical for voice assistants at the moment, but with proper design, you can make sure that users don’t come away frustrated when their questions aren’t answered. Using the principles of visual UX design can help by documenting the typical user journey through a conversation with a voice assistant. You can see examples of those conversation maps in this authoritative write-up from UX designer Cathy Pearl.

While voice assistants haven’t yet replaced humans for more complex conversations, we can certainly use them for many of the mundane tasks we require everyday. Learning to design these interactions will only become more important as voice interfaces become standard worldwide.