Selecting an appropriate user interface

The first decision that you must make is to select the appropriate user interface for your application. Not all applications are well-suited to a SUI; some work best with a visual interface, and others benefit from a multi-modal interface (that is, both a speech and a visual interface).

The characteristics in Table 1 can help you decide whether your application is suited to a SUI.

Table 1. When to use a speech interface
Consider using speech if:	Applications may not be suited to speech if:
Users are motivated to use the speech interface because it: Saves them time or money Is available 24 hours a day Provides access to features not available through other means Allows them to remain anonymous and avoid discussing sensitive subjects with a human	Users are not motivated to use the speech interface.
Users will not have access to a computer keyboard when they want to use the application.	The nature of the application requires a lot of graphics or other visuals (for example, maps or commerce applications for apparel).
Users want to use the application in a “hands-free” or “eyes-free” environment.	Users will be operating the application in an extremely noisy environment (due to simultaneous conversations, background noise, etc.)
Users are visually impaired or have limited use of their hands.	Users are hearing impaired, have difficulty speaking, or are in an environment that prohibits speech (for example, a courtroom).