Designing for Audible Interfaces

Audible interfaces, such as those found in voice message systems and automated call centers, have some special challenges. Navigation is the most critical challenge because it is easy to get lost in a tree of functionality (which these systems almost always are) with no means of visualizing where one is in the hierarchy. The following are some simple principles for designing usable audible interfaces.

• Organize and name functions according to user mental models. This is important in any design, but doubly important when functions are described only verbally, and only in context of the current function. Be sure to examine context scenarios to determine what the most important functions are, and make them the most easily reachable.

• Always signpost the currently available functions. The system should, after every user action, restate the current available activities and how to invoke them.

• Always provide a way to get back one step and to the top level. The interface should, after every action, tell the user how to go back one step in the function structure (usually up one node in the tree) and how to get to the top level of the function tree.

• Always provide a means to speak with a human. If appropriate, the interface should give the user instructions on how to switch to a human assistant after every action, especially if the user seems to be having trouble.

• Give the user enough time to respond. Systems usually require verbal or telephone keypad entry of information. Testing should be done to determine an appropriate length of time to wait; keep in mind that phone keypads can be awkward and very slow for entering textual information.