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:

• Selecting an appropriate user interface
• Deciding on the type and level of information
• Choosing the barge-in style
• Selecting recorded prompts or synthesized speech
• Deciding whether to use audio formatting
• Using simple or natural command grammars
• Adopting a terse or verbose prompt style
• Allowing only speech input or speech plus DTMF
• Adopting a consistent set of global navigation commands
• Deciding whether to use human agents in the deployed system
• Choosing help mode or self-revealing help

There is no single correct answer; the appropriate decisions depend on the application, the users, and the users' environment(s). The remainder of this section presents the trade-offs associated with each of these decisions.