Introduction The SUI guidelines presented here are just that: guidelines. In some cases, the requirements and objectives of particular VoiceXML applications may present valid reasons for overriding certain guidelines. Furthermore, these guidelines address the design points we have found to be the most important in producing speech/audio user interfaces, but are not as comprehensive as those found in a book dedicated to the topic. Finally, keep in mind that while the following guidelines can help you produce a usable application, they do not guarantee usability or user satisfaction; you should plan to conduct usability tests with your application. (See Design methodology.)
Design methodology Developing SUIs, like most development activities, involves an iterative 4-phase process:
Getting started—high-level design decisions Designing a SUI involves at least two levels of design decisions. First, you need to make certain high-level design decisions regarding system-level interface properties. Only then can you get down to the details of designing specific system prompts and dialogs. The high-level decisions you need to make include:
Getting specific—low-level design decisions Once you have decided on the high-level properties of your system, it's time to consider the low-level issues, especially regarding specific interaction styles and prompts. This section addresses the following issues:
Advanced user interface topics The guidelines presented in the previous sections of this section cover the fundamentals of creating a clean, usable SUI. You don't have to stop there, though, if you have the resources and motivation to create a more advanced user interface. The advanced user interface topics covered in this section are: