While Voice User Interfaces, or VUIs, have been around us for a while, the user-centered design of such systems has emerged fairly recently, with the increased development of smart systems and voice assistants. Among the old systems we’re used to are IVRs – Interactive Voice Response systems, like in automated customer support. These systems are notorious for long waiting times, monotonous voices, and confusing menus.

Modern VUI design aims to avoid all these problems and create a positive user experience, whether it is used as a primary interaction method or a supplementary one. What makes it difficult is that people are more reliant on visual information than on auditory one. That’s why the design principles for the VUI development are very different from the ones for the visual UI.

If you need to design your own VUI and want to learn more about the design principles, we’re here to assist you. Let’s explore the basic principles of VUI design, tips on how to make it better, and what is the future of the technology.

The Basics of the VUI Design

Communication between any device and human is a conversation – an output of response to a certain input. When it comes to VUI, the input is the speech, which is then translated to text, which is converted into a command recognizable by the device, that in turn triggers a certain output.

The input is preceded by a certain action from the user, like using a certain phrase (“OK, Google”), pushing a button, or activating a sensor. Similarly, there should be a cue that will confirm that the input is received and the device is working on producing an output.

Before you start designing the VUI, first you need to determine which device it’s going to be used on. This will help you define the technological constraints, like network connectivity and processing speed, and also determine whether the system will work better as a separate system or a part of a multimodal interface.

The next step in the design process is dialogue-based planning. Either directly in the form of a dialogue or by using flow charts, map out the key interactions between the user and the system. Based on this, you can create sample dialogues that can later be used as a wireframe for the interface. For example, the sample dialogue can look like this:

After you determine the “happy” course of action, it’s time to add error strategies in case the dialogue deviates from what you’ve mapped out. This can include re-prompts (“Could you repeat that?”) and escalating errors (when the user makes too long of a pause, fill it with a clarification).

Tips on How to Make a Good VUI

Let’s review some of the good practices that might assist you in making a quality VUI in the form of dos and don’ts:

Do:

• Make sure the user knows in what menu they’re in. Include the description of the action even in the affirmative message (“Sure, I will turn on this playlist”);
• Provide examples of what the user can do in a particular case;
• Give your interface a personality. This can be achieved through both quality voice acting and the conversational flow, like a reaction to recognition errors;
• Use visual feedback whenever possible. If the VUI works in combination with a visual interface, add a speech-to-text visual, so that if the mistake is made it is caught early on;

Don’t:

• List more than three options in a single list, this may confuse the user;
• Use the wake word if it’s possible. Using a wake word of phrase drags the experience out, and can actually be a security threat;
• Focus on specific commands – the natural conversation format provides a much better UX than trying to teach a user-specific thing they need to say to do something;
• Leave any place for double meanings – present any information as concise and direct as possible.

Tools You Can Use for VUI Development

While you can start designing the interface simply with pen and paper, further on in the design process it is better to use specific tools that will help you deal with a large number of dialogue options. Among such tools are:

• Dialogflow – this software is designed specifically to design and integrate the conversation-based interface you develop into mobile applications;
• Flowmapp Userflow Tool – this tool is perfect for building complex diagrams of the user flows, and has a lot of customizable elements you can use to your advantage;
• Adobe XD – another customizable tool, this software can help you to create interactive design prototypes you can later adapt to fit your VUI model.

The Future of Technology

Some experts consider VUI the future of user experience design. The notable reason behind such an opinion is that you can interact with a device without touching, or even looking at it. This has several key benefits the VUI has over GUI.

Firstly, this provides much better technology accessibility. VUI makes it possible to use the technology for people with certain disabilities, including visual impairments, issues with mobility, and more.

Secondly, VUI provides a safer way to interact with public systems. As the COVID-19 pandemic has shown us, touching devices millions of people have used before you can have health risks, which are eliminated if you don’t have to touch them.

Thirdly, this provides a better experience of using a device if you need to focus on another activity. For example, you can take care of tasks while simultaneously enjoying a book.

VUI can potentially benefit various services, from medicine to e-commerce. However, a poor design can ruin the user experience completely, making it frustrating to use. So, become a part of the solution and design your own VUI now!