Unlocking the Power of Voice: A UX Guide to Designing the Right Voice User Interface (VUI) for Your Product

By Thomas DiNatale
March 3, 2023

When considering features to add to your digital product, a voice user interface (VUI) isn’t one you would necessarily think of as a priority — unless your customers are specifically asking for it in your support and feedback channels. For example, do you regularly receive inbound requests like the following:

“Have you ever considered integrating with Alexa or Google Assistant? “Hey, Google, how long has it been since I last (took this action)?” Just something to consider. It would be helpful to me….” 

“Just downloaded the app, and it looks great, and I love the Apple Watch app. It would be great if you could add Siri Shortcuts in the future for handsfree actions via Siri/Homepod.”

If you receive feedback from multiple customers that looks something like the above, your product team has most likely considered integrating VUI into the user experience. And, as you know, being responsive to ever-changing gaps and opportunities in your UX is the surest way to maintain user satisfaction. 

Similar to graphic user interfaces (GUIs), designing the right UX for a voice user interface (VUI) is complex because people have different ideas about how a VUI would benefit them. 

One user wants Google Assistant to give them information about a previous activity to make a decision now. The other user wants Siri shortcuts to record something they’re actively doing so they don’t have to pick up their iPhone and open an app. But, designing for all inbound user requests would most likely require you to support all the available VUIs: Amazon’s Alexa, Apple’s SiriGoogle’s Assistant, Mircrosoft’s Cortana

It may be obvious, but supporting all available VUIs is not only a poor path forward for your UX but also resource intensive for your product and engineering teams.

So where do you start? Do you design for Siri or Alexa? What about Google? Do your users want to retrieve information or record information? And here’s a big one: how do you design and usability test voice experiences when a user interface is non-existent? 

Every digital wellness product is different, but there’s one thing every product team can lean on to integrate a voice-activated experience: a customer-centric UX approach. Here’s our step-by-step guide to designing a voice user interface that improves your product’s user experience.

1. Send a UX Survey to Gather Deeper VUI Usage Insights

You know your users want a VUI extension from inbound support channels, but some questions about specific user needs and how VUIs might fulfill them still need to be answered.

You could conduct user interviews to learn how customers expect to interact with a VUI. But user interviews can be time-consuming, and the insights are purely qualitative. Other methods like session analysis, heatmaps, and usability testing are unlikely to give you accurate insights into hypothetical product features. You need an approach that will provide qualitative and quantitative data on current and future product features.

So, what UX research method should you rely on to quickly gather user feedback and insights? A UX survey. UX surveys are a quick and relatively easy research method to answer your questions and guide your product team.

But before you jump into Typeform and hit send, it’s critical to take the time to design the survey. So here are a few steps to take before you send your survey.

A. First, Define Your Survey Objective

Writing your survey objective should be a quick exercise. The goal is to help you align your team as you determine the scope of the survey, the specific target audience within your user base, and the metrics you want to measure. Using a baby-tracking app as an example, we could define our survey objective as the following: How might VUIs help new parents and caregivers achieve their tracking goals? 

B. Next, Outline Your Themes

When developing your survey themes, consider starting with broader UX themes to set a baseline before focusing on specific product experience aspects. Starting too narrow might confuse participants because they lack context and, as a result, distort your data. For example, in our scenario with the baby tracking app, our research themes could center on the following: 

  • Current product experience: How does the baby tracking app help new parents and caregivers solve their needs? Focusing on your users’ current goals, pain points, and behaviors establishes a baseline for participant feedback as you move into questions about hypothetical features. 
  • Interest & expectations in VUIs: Does the customer currently use voice assistants? If so, which ones? The goal is to create a baseline to understand the customers’ behaviors with VUIs outside our product.
  • Opportunities for VUI: How could a VUI improve your current tracking experience? Your opportunity questions can be open-ended, allowing users to suggest how a VUI best serves their needs. Or close-ended, allowing your team to get quantitative feedback on assumptions about VUI usage.

C. Write Your Survey Questions & Do Two Test Runs

When writing your UX survey questions, be sure to refer back to your survey objective. Doing so will help you write targeted questions that yield the insights you need. Additionally, for your survey to be effective, it’s essential to consider the following when writing your questions:

  • Keep the survey short: Keep the survey short and concise to avoid overwhelming users with too many questions. Focus on the most critical questions that will provide meaningful insights. If you need to ask a significant number of questions, consider using branching logic. Doing so will reduce survey fatigue and improve the quality of your data.
  • Use clear and simple language: Use clear and straightforward language that is easy for users to understand. Avoid jargon and technical terminology that may confuse or frustrate users.
  • Use various question types: Use a combination of question types, such as multiple-choice, open-ended, and rating scales, to gather both qualitative and quantitative data.
  • Use neutral & balanced questions: Avoid language that could influence the participant’s response. 
  • Avoid leading questions: Leading questions can bias your participants’ responses, so avoiding them is essential. For example, instead of asking, “Don’t you think this design is great?” ask a more neutral question such as “What do you think of this design?”

You have alignment on your survey objective, defined your themes, and crafted a great set of questions, and you’re ready to hit the send button. But, before sending the survey to  all your users, do two test runs to smooth out any unforeseen friction. 

First, test it internally to ensure the questions are straightforward and the survey functions correctly. Then, send the survey to a small group of participants and closely watch email open and survey completion rates. You might have to adjust email subject lines, body copy, or the day and time you send to get the desired completion rates.

2. Design Your VUI Dialogue Flow Based on Survey Insights

Insights from your UX survey have aligned your team on how VUIs can best serve your customers. Now it’s time to start designing your VUI user experience. Where do you get started? 

The process is the same as designing for screens: sketch, refine, prototype, usability test, and refine. But rather than having screen flows with UI elements, you’ll design a dialogue flow. 

Like designing a GUI, designing the dialogue flow for a voice user interface (VUI) involves defining the interaction between the user and the VUI. Here are some steps you can follow to design a dialogue flow:

  • Use survey insights to identify user goals: What does the user want to accomplish using the VUI? Are they recording information? Are they tracking information? Is the experience multi-modal?
  • Break the goal into steps: Break the user’s goal into smaller steps or actions that the VUI can understand. For example, if the user wants to record a baby feeding session, the VUI may need to ask questions about the types of foods and amounts the baby is eating.
  • Develop a branching structure: Develop a branching structure that outlines the different paths the dialogue could take based on the user’s responses. The branching structure will help ensure that the dialogue flow is flexible and can handle a variety of user inputs.
  • Design prompts and responses: Design prompts and responses that are clear and easy to understand. The VUI should use natural language and vocabulary appropriate for the target audience and consistent with the brand or product it represents.
  • Always provide feedback: Use confirmation prompts to confirm the user’s request before proceeding. If the VUI encounters an error or does not understand the user’s input, it should provide clear and helpful feedback. Remember, unlike GUIs, VUIs don’t provide immediate visual feedback to users.

Now that you’ve designed dialogue flows you feel confident in, it’s time to conduct usability testing. You can reach out to users who completed your survey and test your designs with them using a technique called Wizard of Oz.

3. Conduct Wizard of Oz Testing to Learn How Users Will Engage With Your VUI

Wizard of Oz testing is a technique used in user experience design to test and evaluate user interactions with your product without building a fully functional system, in our case, a real VUI. Instead, a human “wizard” takes the system’s place and simulates its responses to the user’s actions. Here are the steps to take after recruiting your participants:

  • Prepare the Wizard script: Develop a script that outlines the user interactions and responses the Wizard will provide. This script should cover a range of scenarios that users might encounter while using the product or service.
  • Conduct the testing session: Have the users interact with the Wizard, and observe and record their actions and feedback. In our scenario, the user sits in a room with a device. At the same time, someone from your team poses as Alexa, Siri, or Google, communicating through the device from another room via a microphone. The Wizard should respond to the user’s actions according to the script, using pre-prepared responses or improvisation as necessary.
  • Collect and analyze data: After the testing session, review the recorded data and analyze the feedback from the users. Look for patterns in the data and use the feedback to identify any issues or opportunities for improvement in the VUI.

Use the findings from the usability testing to refine your dialog flow. It’s important to remember that designing a VUI is an iterative process, and you may need to make changes as you receive user feedback. Therefore, you should conduct further testing to ensure the changes have been effective.

Designing a VUI can be challenging, but following these steps, sending a UX survey, designing a dialog flow and conducting Wizard of Oz testing should should help you create a user-friendly and engaging voice interface that meets your customers needs.

Cover Your Bases With a Digital Product Design Consultancy

The difference between creating voice-activated UI versus graphic UI isn’t significant, but some VUI nuances warrant an expert’s eye. If you’re unsure how VUI fits into your product strategy, you will likely benefit from a digital product design consultancy. The UX Strategy team at Everyday Industries can help you integrate usability testing feedback into your product design and development. 

Want to enhance your product with VUI or a different user experience extension? We want to help.